MeproLight M21 Review

In a Nutshell

For infantry and patrol, a matter of a split-second can make all the difference, and for infantry in situations where supplies are hard to come by, the amount of maintenance required by an optic can be make or break. M21 offers a promising solution to infantry and patrol who need something that they can pull from the hip and have ready to go as soon as they are. Other users aren’t going to want it.

Our Rating: 7.8 / 10

  • Accuracy: 8.5
  • Features: 7
  • Optics: 7.5
  • Construction Quality: 9
  • Value: 7

What’s the Scope?

MeproLight’s M21 is a high-quality quasi red dot reflex sight designed for “quick and instinctive accurate shooting”, per the MeproLight website.

Quick Specs

Weight13.12 oz
Size (LxWxH in mm)114x55x70
Waterproof Depth20m
Night VisionNo
Battery LifeN/A
Lens Cover Type​None
​Approximate Cost$450 or less


  • Always ready and doesn’t take any batteries, so maintenance on it is ridiculously low and it’s good to go whenever you are
  • Highly accurate with quick target acquisition
  • Durable and ideal for combat situations
  • Ultra low profile, lightweight, and compact
  • Simplicity means there are few places where things could go awry in this sight
  • Quick release mount makes it super easy to attach and detach


  • The optics wash out in dark rooms when looking toward something bright
  • Poorly-controlled parallax means you may lose focus in situations where you really need it
  • MeproLight’s customer service leaves a lot to be desired
  • Expensive, even if it’s relatively cheap
  • Amber sight may have too low of contrast for your taste

Our Review

First thing’s first: this is a high-quality optic. As in, used by the infantry in the IDF (Israeli Defense Force) good. Of course, it’s not wise to live life by the “good enough for the military, good enough for me” mantra, but it is a promising aspect. Upon mucking around with it a bit, I quickly began to see why it’s used.

First thing’s first – it was quickly apparent that the lenses are nice. I mean, they were just super clear with a fairly good field of view. Not much more to say than that. Well-constructed glass that’s well-seated and well-sighted means, ultimately, that the sight just has good vision. At this price point, it’s honestly a bit better than I expected. On the other hand, the amber color of the sight has fairly limited contrast, which may make it hard to differentiate between targets.

All in all, the sight is super accurate. There is a drawback in the sense that the parallax isn’t well-controlled. This isn’t a huge issue all of the time, but more compromising or precarious situations may make it hard to get and maintain focus.

The real appeal of this sight comes down to the fact that it doesn’t take any batteries. This is super convenient for obvious reasons. You don’t have to carry around any spares or worry about the M21 dying on you. There aren’t any electrical components that might malfunction or break on you. It’s pretty much a true what-you-see-is-what-you-get sight, and what you see is a bright and responsive optic.

The reticle of this sight is super bright and obvious in sunlight and you won’t have any problems acquiring targets. The reticle itself can take many forms; we sprung for the unique triangle shape. All reticles are well- designed and allow you to efficiently focus. In indoor environments, it’s a little bit dimmer but still fairly clear. In night-time or no-light environments, the scope operates well using an integrated power system to provide illumination in these circumstances.

One problem that a lot of people have encountered is that the reticle, unfortunately, washes out when you’re in a dark room looking at a light source, like at or outside of a window. Again, this can be corrected by co-witnessing, but some people may not want to co-witness just to have an always-usable gun.

This sight is particularly well-suited to cold or arid environments for two reasons. Firstly, in extreme temperatures, batteries drain much faster than they may under more temperate conditions. Obviously, not having batteries on this sight means you never have to worry about batteries dying on you. However, there’s another less obvious reason: snow and ice reflects light, creating a super bright environment, and arid environments tend to be very sunny by their very nature. In either case, you have a recipe for a super-bright reticle in daytime combat conditions. Given that the IDF is fighting in arid conditions, it’s clear why they might choose to give their infantry a sight like the M21.

Installation of the unit is simple, and you don’t need a spacer to take advantage of this sight either. After mounting, zeroing is a snap and the sight should hold zero for a long time to come. The quick-release mount is also super nice, making cleaning stress-free since you can just detach the mount for storage and clean your weapon properly.

Moreover, this is a military-grade sight. Because of this, it’s built to take a beating, and it’ll serve you well in this capacity. Pretty much, you can expect it to take whatever mess you two might go through together, and do so with a smile. Whether or not this durability makes up for some of the optical shortcomings is for you to personally decide.

Let’s talk value. The biggest drawback of this unit is the fact that it’s a little expensive for what it is. While it’s cheap compared to its competitors, it’s a little expensive when you take into account the limited set of features and the narrow situational scope where it would actually be of use to you, outside of close quarters battle in open-air or daylight indoor situations. This is worsened by the fact that MeproLight has far from the best customer service. In fact, getting in touch with them and resolving problems can be fairly frustrating.

At the end of the day, though, there’s not a lot to be said for this sight. The fact that it’s always on and doesn’t require any batteries means that it’s always ready for you, whenever you may need it. It’s highly accurate and the idiosyncratic reticle options make it easy to find and keep your sight on your target – though it won’t need to stay on them for long, thanks to the pinpoint precision. It’s built for daytime fighting in close quarters situations, and outside of that situation, you may find yourself needing to rely on other optics for illumination and clarity.  But depending on your needs, it might be perfect for you.

Should You Buy It?

This is a niche sight intended for a niche audience. But bearing that in mind, if you’re in a situation where you’re primarily vulnerable in open-air situations, where quick reflexes are of the utmost importance, and especially if where supplies like batteries are hard to come by, then this is the sight for you, and Yes, you should buy it. This includes folks like infantry and people on  patrol. It performs well in uniform lighting situations but falters when confronted in the dark with a light source. For people looking for general home defense, you probably don’t want the M21 for this reason.

Closing Comments

For the general-purpose shooter, looking for something to shoot targets or to defend their home with, this is probably not the most ideal sight. But for the niche audience, this sight is intended to accommodate, there are few better options, and if you’re in this sight’s target market, you really can’t go wrong.

If you are going to a hunting expeditions for a pro-longer period of time, don’t hesitate to upgrade your hunting binoculars and hunting tent with something better, more durable, and long-lasting.