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


Great Micro Sight!


This is a great sight for my G-48!! It's well built and fits the G-48 VERY well!! PA has another hit on their hands!

The only problem is that the supplied screws are too long for one side of the sight. The right side screw impinges on the plunger tube, making it unusable. So I'm using the original MOS plate screw. Hopefully it's long enough to grip...

The too long screw is the only thing that prevented me giving this 5-Stars.

Perfect fit for my 43X MOS!

by -

Simple red dot that works great. No shake awake or auto off, but that's fine. I was able to direct mount it to my 43X MOS with no plate needed. And it co-witnesses, which is great because I can always see the target, even if the battery dies.

*FYI: I had to change the screws because the ones that came with it caused the ejector to lock up. I used the screws that were already on my OEM MOS plate and now it works perfect.

For Sig p365XL

by -

If you’re going to be putting this optic on an Sig P365Xl, this optic does not come with the correct screws. You’ll have to go get the screws at your local hardware store. You’ll need screws: M3.05
9.6mm length. This is something that I could have been on the description or on the user manual.

A Question


What are the length, width, and height of the Classic 21mm Micro Reflex 3 moa?



Perfect optic for p365 finish is really nice, all aluminum, clear glass, for the money it can’t be beat, only con is that it doesn’t have shake awake

Great Site for the Money

by -

Installed on my sig P322 very crisp and accurate. Only wish the would send more screw options and inserts for smaller screws, it would be worth paying more for all the hardware opinions.

Perfect out of the box


Mounted directly onto the Glock 48 MOS replacing the MOS cover plate perfectly. Didn't even need to change the screws. Dot was centered perfectly for a 25 yd zero. For the price and quality, this is a winner all around.

Works great


I put this on a PSA Dagger that I couldn’t pass up for the price. The optic is the best part of the’s clear and bright. It has held its zero through 250 rounds. I’m not sure the pistol will.

Good and Bad

by -

This is a pretty great Micro sight for the money. I bought it for a G48, but the problem is PA supplied two screws that were the same height. This is no good since the right side screw needs to be shorter so as not to impinge into the depressor plunger channel. So this is a no-go without a shorter screw.

Thank you for taking the time to speak with me today. We appreciate the opportunity to get the necessary screws sent out and get this resolved. Please do not hesitate to reach out if you have any questions.

very nice

by -

Optic fit my 43x MOS perfect. Not sure what the bag of longer screws are supposed to work with. Trying to locate screws that actually fit. The plate screws that came with the gun barely stick out the bottom of the optic. hence the four stars. will update when I find screws and get some rounds through it.