Cloud Defensive REIN [Gear Review]


If the competition for the brightest weapon light were an arms race, then Cloud Defensive would be a Superpower. They continue to develop innovative, durable, ergonomic, and hilariously powerful weapon lights. Cloud Defensive is probably best known for their Optimized Weapon Light (OWL), and though they were a relatively new name when the OWL hit the market, its success rocketed them to the varsity list of weapon light manufacturers. 

Following the OWL, Cloud Defensive designed and manufactured the REIN that, on the surface, seemed to follow the design of many weapon lights already on the market. However, in true Cloud Defensive form, this new light was packed with innovation, ruggedness, and ergonomics the company is known for.

Purpose of REIN.

Though Cloud Defensive’s OWL met a number of needs, there still were applications where the conventional light with a separate wired pressure switch is useful. These applications include rifles with longer rails, where it may not be possible or ergonomic for a shooter to reach the controls of the OWL. Another application could be where the light would be mounted alongside IR illuminators and lasers, providing limited real-estate on the rail. 

My personal and professional need for the REIN falls into the former scenario. The AR upper I am using has a 13.5 inch rail with a 16 inch barrel, and in order to avoid barrel shadow, I needed to mount a light pretty far forward on the rail. If I were to mount the OWL where I needed it, my support grip would have been uncomfortably far forward on the hand guard. However, with the REIN (Rail-mounted Environmental IllumiNator), I can mount the light forward and still have the control switch mounted in an ergonomic position along the top Picatinny. 

Illumination Innovation

The phrase “If it’s not broke, don’t fix it” has merit for a reason and it seeks to buttress against innovating for the sake of innovating. And in the field of mounting flashlights to rifles, one might assume that any innovation might provide marginal improvement and would more likely be a marketing gimmick.

However, Cloud Defensive shattered these preconceptions with the OWL and they did it again with the REIN. In this Gear Review, I will attempt to address each innovation (forgive me if I miss some). I will also discuss what I like about the REIN, any critiques I have, and how it compares to the OWL. 

Lens Replacement

Many weapon mounted lights are designed such that if the lens were to be damaged, the end user would either need to send the entire light back to the manufacturer for a warranty repair/replacement, or be forced to purchase an entirely new light. I do not know if this is simply a design oversight or planned obsolescence, though I do know that it can be frustrating. 

Weapon light lenses are generally the most fragile as well as one of the most critical features of a weapon light. Lens damage can occur in daily use, training, force-on-force, on deployment, or any number of activities. So, Cloud Defensive introduced their field serviceable lenses that can be replaced quickly by the end user. These field serviceable lenses were first introduced with the OWL and were adopted into the REIN. 

Whenever I participate in Force-on-Force training, I like to train with the same gear that I plan to use at work or in a self defense setting. However, simulation and UTM paint rounds are very capable of breaking the glass of optics and weapon lights. Prior to owning the OWL or REIN, this could mean risking an entire light’s usability in training. Though, with CD’s field serviceable lenses, I could just swap out a broken lens with an $8 replacement lens ($8 vs a few hundred on a new light). Furthermore, the OWL and REIN lenses are interchangeable. 

Cable Routing

When lights were first mounted (or taped) on rifles, the control switch was just the ordinary end cap button found on most Maglights. However, companies began to develop pressure/tape pads/switches that would be wired to the light and then allow the enduser to place the switch in the most ergonomic place so that they were not sacrificing their grip to actuate the light. 

However, these switches came with varying lengths of wire that needed to be routed in such a manner that it would not snag easily. This wire consolidation was accomplished using tape, zip-ties, rubber bands, and other high speed low drag cool guy devices. 

Cloud Defensive solved this issue beautifully with the OWL. An offset mounted light and an integrated pressure switch. Then when CD created the REIN, which uses a cable, they designed an innovative solution to store excess cable. 

CD’s REIN accomplishes the wire routing and consolidation problem in two ways. First, the location at which the wire feeds out of the light body can be timed so that the wire exits the light body in the least obtrusive manner. Second, the excess cable can be routed under the pressure switch picatinny mount. 

Power Supply

I’m going to do my best to not turn this Gear Review into a discussion on battery technology, but I feel it’s important to discuss why I believe CD chose the battery they did. If you don’t care, just scroll to the next section.

The most common batteries used to power weapon lights or pretty much any other tactical electronic are CR123A primary lithium-metal batteries. These batteries are used to power handheld flashlights, weapon lights, night vision, and a slew of other tactical electronics.

You might be wondering why CR123A batteries are so popular in Military and Law Enforcement compared with common civilian batteries like the AA or AAA type batteries. Well, for one, CR123A’s can reliably operate in more extreme temperatures than common civilian batteries. Moreover, CR123A’s have a much longer shelf life, so Uncle Sam doesn’t have to worry about purging warehouses stocked with these batteries if nobody wants to play war for a few years. Supposedly, CR123A’s can be stored for 10 years without issue and while conserving most of their charge. 

So, you might be thinking that with all those benefits, why would anyone want to use anything other than CR123A’s in tactical electronics? To answer that, there are three primary reasons:

  1. They are non-rechargeable
  2. They are expensive ~$1.50 per unit
  3. They do not perform well in high output lights

The inability to recharge or top-off a partially charged battery means that you never really know how much charge is left. So in a Mil/LE setting, this often results in partially charged batteries being swapped out with fresh ones (i.e. waste). Some deployed units even swap out their CR123A batteries every day or after each patrol just to ensure the batteries don’t die during a patrol. 

Rather than follow the traditional model of using the popular CR123A to power weapon lights, Cloud Defensive chose to use the 18650 lithium-ion for both their OWL and then again for the REIN. You might be asking yourself what the heck an 18650 is and if you are, you’re not alone. Prior to owning the OWL, I had no idea what an 18650 was. I thought it looked like an oversized CR123A, but this couldn’t be further from the truth and Cloud Defensive goes out of their way to make the point that using a CR123A in one of their lights will cause catastrophic electrical failure and will void the warranty. 

So, what exactly is an 18650 lithium-ion battery and how does it compare to the long trusted CR123A? To start, lithium-ion batteries are nothing new. They have are used for laptop batteries and are used in most cell phones, like the iPhone. Lithium-ion batteries are also used in Tesla’s electronic cars. Lithium-ion batteries are also rechargeable and while they are more expensive up front, they are much more economical in the long run. 

Let’s compare the long term cost of 18650 and CR123A. In the following calculation, I assume that the 18650 can only last 300 of the maximum 500 recharge cycles. Not sure if this assumption is reasonable or overly conservative, but I could not find information on lower end charging cycle ratings. Also, CR123A’s are non-rechargeable, so they only last one cycle. 


Therefore, the life-time equivalency cost of using CR123A’s vs 18650’s would be around $1,000. You might argue that not many people would ever see 300 charging cycles and so let’s calculate the cost per cycle (remember CR123A’s last 1 cycle). To do this, we simply need to divide the cost by the number of charge cycles. So for a pair of CR123A’s we divide $3 by 1 cycle, giving us $3 per cycle. And for the 18650’s, we divide $20 by 300 cycles, giving us $0.07 per cycle.

Ok, enough of that, let’s get back to the REIN!


Speaking of power, let’s take a moment to discuss how hilariously bright the REIN is. This light is stupid bright and the throw is incredible, while still providing great spillover for peripheral illumination. 

The large body is rated at 1,400 Lumens and 60,000 Candella. I’m not going to go into the difference between Lumens and Candella, though if you want to read my explanation, go here. Put simply, Lumens is a measure of the usable light, while Candella effects that center hot spot and the “throw.” The REIN has plenty of both. 

If you are concerned that the REIN is “too bright.” Don’t be and I’m not even convinced we have arrived at that point yet. 

Battery Spacer

Vibrations induced by recoil can compromise electrical connections over time. 

Just about every weapon light on the market has its batteries oriented parallel to the barrel. Therefore, as the weapon recoils rearward, the battery can slide around inside the light body if not secured. In most lights, batteries are secured by the compressed spring in the end cap. This means that if the recoil is substantial and overcomes the spring tension, the other end of the battery will momentarily separate from its terminal. 

Cloud Defensive sought to remedy this with their proprietary “Battery Jack.” The Battery Jack is a plastic spacer that presses the 18650 battery against the contacts of the light head, while still allowing the spring to make positive contact with the rear of the battery. Thus eliminating the movement of the battery with respect to the light body and the compression of the spring during recoil. See the images below for how this innovative feature works. 

1. Locate Battery Jack
2. Unscrew Battery Jack (Counterclockwise)
3. Insert 18650 Battery
4. Screw on Light Head
5. Observe space between Battery Jack and Battery
6. Screw In Battery Jack until it is secure against battery

Body Size

Depending on your needs, you can select between two light body sizes. The size will dictate the size battery it can hold and subsequently the output and run time. I personally run the longer body size on my patrol rifle but the shorter body might be more appropriate for a shorter gun with less real-estate. As far as output, I don’t think you would be able to detect any noticeable difference between the two size variants; however, the difference in run times between the two options is substantial. I don’t want to have to worry about my battery dying so I prefer the larger option, providing a 1.5 hour run time instead of 30 minutes. 


55,000 Candela

1,300 Lumens

35 Minute Run Time


60,000 Candela

1,400 Lumens

1.5 Hour Run Time


One noticeable feature of the OWL and REIN is their light color temperature when compared to other brands. Cooler light is the lighting you would see in an operating room, LED lights on newer model cars, or in those new Christmas lights. It’s that very white, almost bluish light. Warmer lighting has more of a yellowish hue. The “temperature” of the REIN light is 4,000 Kelvin. This temperature is somewhere between Studio Lighting and Horizon Daylight

Cloud Defensive states that the reason behind this is so that the light can “penetrate photonic barriers better.” Make sense? Probably not and you are likely wondering what the heck a photonic barrier is. I was, but after a bit of research it seems that a light’s ability to penetrate a photonic barrier is just the ability to enable its user to see through another bright light pointing back at them. Think of a car’s headlights or a threat pointing a bright light at you. 

Supposedly, another benefit of warmer light is that it aids with color contrast.

Other Features


Shockproof refers to an item’s ability to be dropped from a significant height or receive a hard impact while still remaining functional. CD states that their lights are shockproof and to back up these claims, they put out videos of them torturing their lights well beyond that which would be expected in ordinary use.

Waterproof (IPX8 100 ft for 24 hours)

The REIN has a waterproof rating of IPX8 and can withstand 100ft of pressure for 24 hours. This is well beyond what a weapon light should encounter unless you drop it overboard (#iLostAllMyGunsInABoatingAccident).

Ships with Picatinny Mount

The REIN ships with an in-line Picatinny mount and while this is great if you have a quad rail and it’s better than not having any mounting options from the factory, it doesn’t really do much for people who only have picatinny at the 12 o’clock position. Just keep this in mind when ordering and that you may need to order an additional rail interface. 


As you can probably tell by now, I love the Cloud Defensive REIN. However, just as with any other man-made device there are flaws, and while the REIN doesn’t have many, I want to address the ones that I have identified. Note, these critiques are my opinion and I could be wrong. 

Pressure Switch Mounting and Cable Damage

With innovation comes challenges. CD’s remote switch wiring design allows for the cable to be concealed under the remote switch mount body. As you can see in the picture below, the wire exits the remote switch at the bottom and then must be routed to the left or right such that it runs between the Picatinny of your rifle’s rail, then out of the side or down the channels along the side. 

Once again, this design is brilliant and enables you to conceal much of the cable that would have otherwise been exposed to snagging and damage. However, it can be difficult to route the cable due to the limited space between the Picatinny and the remote switch. I struggled quite a bit with wiring and mounting the first switch I received and this resulted in the eventual damage to the cable’s outer layer. Mind you, this did not effect the reliability of the switch as far as I could tell. 

Thankfully, CD has excellent customer service and they replaced my remote switch for free. And I have not had an issue with the new remote switch. Also, the newer switch has a textured exterior and a different color spring, both indicating that CD has redesigned it slightly. 

Original Switch with cable damage
New Switch on left
New Switch on left

Hole Patterns on Mounts

The following critique is not on the REIN but on the optional mounting interfaces offered by CD. Now, I do not think that CD manufactures these in house because they look nearly identical to those offered by Haley Strategic and Arisaka Defense, minus the logo. Though, I could be wrong. 

The qualm I have with the mounts is not a failure I have personally experienced, but one I perceive based on my experience as an engineer. If you’ll notice the images below, I have circles the holes that the light body interfaces with. The light body only has two fasteners but they offer a variety of holes to enable the end user to fine tune the exact placement of the light so that it does not interfere with other mounted gear. 

In my opinion, these hole patterns seem far too close together, thus threatening the structural integrity of the interface. Bear in mind, I have not done the Finite Element Analysis, nor have I tested these mounts in a lab to determine when they will fail and where that failure will likely occur. Moreover, these hole patterns are used by many other weapon light manufactures and Arisaka’s hole patterns are overlapping. Nonetheless, when I see how thin the material is that separates each hole, I can’t help but think that it is compromised. 

On the other hand, this could be a designed failure point, so that if the light were to get snagged on something or were to fall from a great height, this interface would fail, thus preserving the light and the rail. 

Torrent Inline M-LOK Mount
Torrent Offset M-LOK Mount

Remote Switch Mounting Screw Length

The remote switch consists of 3 parts (actuation switch and left and right picatinny hooks), two screws, and two nuts. In order to mount the switch to your picatinny rail, you must first assemble it, then route the cable, then hook the picatinny mounts on either side of the rail before tightening the two screws. 

Whenever I mount the switch, it seems as though the screws should be a couple millimeters longer to provide more space between each side of the picatinny mounts. The problem only presents itself when I am attempting to mount the switch and once I tighten down the screws, there is no issue.

However, I believe that if the screws were a couple of millimeters longer, it would make the cable routing and switch mounting process much easier. I would bet that CD does not manufacture these screws in-house, but they are ordered from a third party, so the design team may be running into an issue where the next length of screw is far too long and would protrude out too far when screwed in place. 

Battery Jack Tool

The final critique I have is nit picking, though I still want to mention it.

In order to tighten the Battery Jack, you either need to use a finger, given it’s small enough, or another long tool like an Allen wrench to spin the crown of the Battery Jack to the desired position. 

When the light is not mounted to the gun, it is not that difficult to use your finger to tighten the Battery Jack, but when it is mounted this becomes challenging and I typically resort to using a tool. While this gets the job done, I don’t like the fact that the tool is touching and scraping against the internal threading that the Battery Jack screws into. I have not noticed any damage beyond worn paint, but over time this may be an issue. 

Therefore, I would like future versions to include a plastic tool that could be used when tightening down the Battery Jack. 


As far as quality, attention to detail, and innovation, both the OWL and the REIN are on par with one another. Though, I would like to compare some of the differences between the two lights to enable you when determine which one fits your needs. 

Tail and Head Cap Interface

Aside from the fact that the OWL features an integrated tape switch and the REIN has a remote switch, the most noticeable difference between the two lights is how their tail caps and light head interface with the body. 

The OWL tail cap and light head used a unique Quick Disconnect via CD’s patented lug system, meaning that there are no threaded components, aside from the bezel holding the lens and the picatinny tightening screw. When I first received the OWL, this Quick Disconnect lug system took some getting used to. However, over time I began to prefer it to a threaded interface because it was much faster and I need not worry whether the component was screwed on tight enough. 

The REIN uses a more traditional threaded head and tail cap interface. Due to the unique design of the REIN tail and how it allows you to time the exit position of the cable, I can understand why CD used a traditional screw on design. The head probably could have been designed similarly to the OWL, but this would likely add to the price and overall size. 

If you are concerned with achieving the same tightness whenever removing or reinstalling the tail and head, just use a paint pen to mark the correct tightness. 


Aesthetically, the finish on the REIN is much different from the OWL. The OWL has a very flat rugged finish which somewhat outwardly projects the durability of the light. Comparatively, the finish on the REIN has a more glossy finish, common among many weapon light bodies. Note, I have seen some reviews featuring REINs with a similar finish to the OWL.

Handguard, Barrel, and Arm Length

The main reason I wanted the REIN was to mount to an AR upper with a 13.5in rail. If I were to mount the OWL on this rail length comfortably that would not compromise my support hand grip, the rail and barrel would block a portion of the light and cast a large shadow. However, with the REIN I can mount the light further up the rail and then mount the switch further back. 

When determining which light to use, it is important to consider the rail and barrel length of the weapon it will be mounted to as well as your arm length and where your support hand grips the rail. 


As I stated previously, Cloud Defense is a superpower if the competition for the brightest light were an arms race. Both the OWL and the REIN put out some serious lumens and candela, though the REIN has the OWL beat by about 150 lumens and 5,000 candela. When I compared the OWL and the REIN side by side, the candela was not very noticeable; however, I could detect that the REIN seemed to have much more “throw” than the OWL. 

Actuation (Momentary and Constant On)

The OWL’s control switch consist of a long pressure pad that will either provide momentary On or constant On, depending on how long you press the pressure pad. If you press for longer than 0.25 seconds, it will only stay on as long as you are pressing the switch (momentary on). However, if you tap the switch, it will stay on (constant on).

The simplicity of this system is great and eliminates the need to consciously process mechanics during high stress situations. However, on some occasions I have attempted to press the switch for a brief moment and what resulted was the constant on feature. 

The REIN switch consist of two buttons. One is for momentary on and will only perform the momentary function regardless of how quickly it is pressed. While the other button is for constant on and it provides a tactile click when pressed. Also, the tail cap of the REIN is also a button that does the momentary and constant on that is common to most tail cap switches. Note, the remote switch and the tail cap switch are on independent electrical circuits, so if the switch cable is severed, the tail cap switch will still work. 

Personally, I prefer the REIN switch to that of the OWL and I hope that future OWL generations will adopt the dual pressure pad.

Final Thoughts

Overall, the REIN is an excellent weapon light. It checks all the boxes and then some. If you are looking for a weapon light for your gun and want something with a high output and great durability, then the REIN would be a great choice. 

Where To Purchase

Until next time...

Train To A Higher Standard!

Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.