Primary Arms Classic Series 21mm Micro Reflex Sight - 3 MOA Dot

Manufactured by Primary Arms
MPN: 810035
Manufactured by Primary Arms
48 Reviews

In Stock

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The Classic Series™ proves that entry-level optics don’t have to be poor quality optics. Unlike some other brands, Primary Arms doesn't use the word “value” as a euphemism for “junk”. Classic Series red dots are perfect for the budget conscious and the new shooter. Every product is inspected in their facility in Houston to ensure you are receiving the best quality product as the other three tiers. These red dots are backed by the same excellent customer service and support as all other Primary Arms products.

The Primary Arms MRSC Micro Reflex Sight is a continuation of the new line of red dot sights designed specifically for mounting to pistol slides. The Micro Reflex Sight is optimized for compact and micro compact pistols for concealed carry as it features a slightly smaller 21mm lens to keep the profile as slim as possible when mounting on smaller pistols eliminating any overhang on the slide. Even though the lens is smaller than the mini, the square profile offers an unobstructed field of view allowing you to have a clear sight picture every time you present your pistol. It utilizes the RMSc footprint for a wide range of compatibility with milled slides and adapter plates and houses a bottom mounted CR2032 battery offering up to 40k hours of battery life on the medium setting. With 10 total illumination settings, and a daylight bright 3 MOA red dot, this reflex sight is sure to be quick to pick up and easy to use. The lens is fully multicoated for scratch and fog resistance and the 6061 Aluminum housing is extremely durable. If, you are looking for a new red dot for concealed carry you can't go wrong with the Primary Arms MRSC.

Note: After 12 hours of illumination continuously running, the illumination will turn off. To turn the illumination back on, press one of the brightness adjustment buttons and the reticle will reappear.

  • Fits RMSc footprint
  • Compact 21x15mm lens
  • Optimized for micro-compact pistols
  • 3 MOA Red dot
  • Includes CR2032 battery
  • Up to 40k hour battery life
  • Auto-off turns off illumination after 12 hours
  • 10 Brightness settings
  • Compact and lightweight design
  • Fully multicoated lens
  • Backed by Primary Arms Optics Lifetime Warranty
See More


Battery Life25,001 - 50,000 Hours
Battery TypeCR2032 3V Lithium Coin
BrandPrimary Arms
Brightness10 Settings
FinishHardcoat Anodized
Manufacturer.Primary Arms
MaterialAluminum - 6061-T6
Mount CompatibilityShield RMSc
Optic SeriesClassic
Reticle3 MOA Dot
Reticle ColorRed
Weight.56 oz.
  • Learn More About The Primary Arms Micro Reflex Sight
  • Check Out The Micro Reflex Sight In Action
  • Micro Reflex Sight Review: Beyond Seclusion
California Prop 65 warning

 WARNING: This product can expose you to chemicals, which are known to the State of California to cause Cancer and Reproductive Harm. For more information go to

Ratings & Reviews

48 reviews


Fits like a glove


Purchased this because I wanted a dot to start with until I can purchase a Holosun down the road And I also didn’t want to deal with the hassle of purchasing a mounting plate. This fit directly to my Glock 48 MOS. It came with everything needed to install minus the thread glue. But the battery is located under the red dot so I chose not to use it anyway. Hopefully this info helps someone else. But all in all happy with my purchase.

Can’t find right screw?

by -

Just like the title says I can’t find the right screw for it and I have a bunch of optics screws of different kinds.the ones that fits are too long that it pins the plunger.the optic itself looks really good but another problem is the bottom mount battery

Pretty Good

by -

Dot seems to work and hold up well. Been carrying it around, and put about 250 rounds with it so far and its held zero. Clear glass and Daylight bright. The only thing I wish is that it either had an auto on or didn't automatically turn off. I'd be fine with leaving it on but it turns itself off over night... So at least once or twice a day I have to check and turn it back on usually.

Good for what it is, I guess


I buy a lot of stuff from PA and generally have a nice experience. This, however is just inexcusable. Luckily, it was a gift. A mini reflex this size only has one real use - on a defense weapon. And to not have a shake awake on a sidearm is idiotic. I understand wanting to squeeze every dollar out of the marketplace, but pushing people to a slightly higher price point is actually in their best interest here.

Having said said that, the red dot is fine. It's a dot. And red.

Excellent Red Dot

by -

I bought this red dot sight about a month ago. The sight looks to be very well built and rugged, and looks just right on my Glock 48 MOS. Zeroing was quick and easy. Only a couple of hundred rounds have been shot while this sight has been on the pistol, but I anticipate no problems, I would buy another if needed.

Great Dot

by -

I’ve only had trijicons this is my first time breaking the chain and no regrets. It’s on a FN Reflex works great. Only complaint wish the dot stayed on.

Perfect fit for a Glock 43x

by -

Absolutely love this sight so far. It fits perfect on the Glock 43x and man does it look good. Quality seems on par with the big name brands, the dot looks good, and it came with a plethora of different sized screws as well as some thread locker.

I’d highly recommend this sight.

Great value

by -

This optic is what the Romeo Zero should have been. Spend the same money with PA and get twice the quality. The zero has a plastic body and is essentially junk. Get this instead you’ll be much happier.