Primary Arms 3X LER Red Dot Magnifier - Gen IV

Manufactured by Primary Arms
MPN: 510003
Manufactured by Primary Arms
57 Reviews

In Stock

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Note: This magnifier is not compatible with the Unity FAST 30mm mounts.

The Primary Arms Long Relief 3X Magnifier (Gen IV) is waterproof and fog resistant. Place the magnifier behind your red dot or holographic reflex sight to instantly magnify the sight picture at 3x power. The new Gen IV model has a longer eye relief, wider field of view and improved clarity to provide an enhanced user experience. The integrated diopter provides a fast focus ability to keep the image clear. Azimuth and elevation adjustments keep the dot centered in your field of view. A rubber armor sleeve protects the body of the optic from harsh impacts. This tough magnifier features a lifetime warranty.

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BrandPrimary Arms
Exit Pupil Diameter8.00 mm
Eye Relief2.64 in
Field View 10037.93 ft
Manufacturer.Primary Arms
Mount Compatibility30mm
Optic SeriesClassic
Weight7.9 Oz
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

57 reviews


This is the one!


I have owned both the Eotech G33 and Vortex VMX-3T and much prefer this magnifier. The eye relief is excellent and allows me to keep my normal cheek weld when I move the magnifier into position (I had to move my eye forward for both the Eotech and Vortex). The optics are crystal clear, and it works extremely well with my Aimpoint T-1 and my Primary Arms MD-ADS. One very minor nit is that the caps need to be removed and a tool used to re-center the red dot when moving the magnifier from rifle to rifle. It is really just a personal preference thing to have the dot centered (PoA and PoI don't change when adjusted), and I would like to be able to do a quick finger adjustment when I hot swap the magnifier. I highly recommend this magnifier! I would also recommend the AD swing mount to go with it. I have the absolute co-witness version, and the magnifier does indeed clear my Magpul MBUS when I swing it out on all three of my rifles on which this magnifier has been mounted.

Been waiting for this!!!


I was on the fence on getting the aimpoint magnifier but i couldn't see my self shelling out that much cash for 3x zoom. So when i saw PA was making a gen IV of theirs, i scooped it up...looks great on the rifle and the turrets to focus the red dot to the center is nice. Cant wait to get to the range.

Worth the wait!


I've been waiting months for this to get into stock and was about to say F'it BUT glad I didn't!!!!! eye relief is perfect and a steal at $99!!!!! PA QD mount is awesome also! The service is always good.

Buy GenIII if you can find it...


So, I now own both Gen III and IV. I was waiting for Gen IV for months. I actually broke down and bought a UTG unit a few weeks ago, but returned it a few days before Gen IV went on sale. I wanted Gen IV that bad...Well, gen IV unit is slightly lighter (good) than Gen III, but the "rubberized" cover on Gen IV plain sucks. It looks cheap. Compared it my my Gen III... no comparison. Gen III looks "pro" made, Gen IV looks like a Chinese knock-off but with a good eye relief. I also bought a PA QD flip-to-side mount. Same as my Gen III setup. The new mount has noticeable play in it. The old one is solid like a rock. So overall, I put my Gen III setup back on my 9mm AR15 right behind the TRS-25 and put the Gen IV into the "parts" drawer. When I get another red dot I will take the IV out. Overall, I would have not bought it if I could "touch-n-feel" it first. I am sure it's a good product and will work for anyone without the Gen III (if u have it - keep it!)

Very impressive


Super fast shipping as always with Primary Arms. The product is very solid feeling and has great optics. The eye relief on this model is on par with the $500 magnifiers. I just couldn't justify spending close to what my AR cost on a magnifier. This fit the bill and then some. You wont me sorry. Please note that with any optic you AR will gain a bit of weight.

Great magnifier


The magnifier lined up perfectly with the Bushnell TRS-25 on my AR-15. Purchased along with the PA flip to side mount. Quality product. The long eye relief is as advertised at about 3.5 inches. Focused easily. Made zeroing in at 100 yards quick and painless. Great customer service. I'll be a lifelong customer if they keep releasing products like this.



I attached this with: 'American Defense Magnifier Swing Off Mount - Lower 1/3rd Co-witness' - Works beautifully with my Holosun HS503C! Lines up perfect!

Incredible magifier at a very attractive price.


I am building an AR-15 for my son. I bundled this 3x LER Magnifier and swing mount and chose overnight shipping and got it the very next day. I installed it and everything went together perfectly. I put the rifle to my shoulder and after a few very easy and minor adjustments the sight picture behind an Eotech 517 was brilliant crisp and very clear. Absolutely no smudging of the center dot inside the reticle. Compared to my Eotech G33 magnifier on my Daniel Defense the sight picture is so close to being the same! Sure it's a bit larger in size than an Eotech but not by much. The body is very rugged and the glass DOES collect as much light even on the overcast day that we are having today. Honestly If I had known then what I know now.....I would own 2 of these things and saved over $400!!! Way to go Primary Arms! Nice piece of hardware for such a low price!!! Get one and pat yourself on the back for the $$ you just saved!

works great


I have two of these current and previous Gen. Both work like champs! I don't see well in the distance so 25 yards without magnification would always be a problem. Not anymore. Good Stuff

Great Value


Very impressed with this magnifier! Very good eye relief. This is the first magnifier I have used so I don't have a lot to compare it too but for the price I don't think you can beat it. I am sure it's not the quality of an Eotech or Aimpoint but its also not the price of an Eotech or Aimpoint. Unless you are getting deployed I would strongly recommend looking at this before dropping $400 on a magnifier.