Primary Arms SLx Full Size 3X Magnifier

Manufactured by Primary Arms
MPN: 510012
Manufactured by Primary Arms
27 Reviews

Out of Stock

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The SLx FS 3x Magnifier supplements your red dot or 1x prism with added magnification when engaging targets at medium to long distance. This magnifier is part of the SLx optics line. SLx optics built the reputation for innovation, reliability and value. All SLx optics undergo rigorous field-testing during development to best serve you in any environment.

Compatible with the most popular mounts on the market, the SLx FS 3x Magnifier is a versatile addition to any close-quarters optics setup, and the enhanced glass quality and wide field-of-view ensure that the user can always get a clear view of their target. Though the SLx FS 3x Magnifier weighs a mere 8.45oz, its durable construction protects it against the repeated shocks and impacts of duty use.

As with all other Primary Arms Optics products, this magnifier comes backed with a limited lifetime warranty and commitment to customer satisfaction.
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BrandPrimary Arms
Exit Pupil Diameter8.50 mm
Eye Relief2.80 in
Field View 10040.5 ft.
Manufacturer.Primary Arms
Mount CompatibilityPrimary Arms 2-Bolt Magnifier Mounts
Optic SeriesSLx
Weight8.45 Oz
  • New SLX 3x MFS
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

27 reviews


PA SLX 3X Magnifier

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Got mine today. Works perfectly with a G2 Cyclops and the PA mount for the 3X. Very clear glass. Took about 5 minutes of fiddling to mount and adjust the diopters. Perfect 3X sight picture. Remember to run the diopter on your Cyclops as far OUT as possible while still keeping a clear sight picture, then start with your diopter on the 3X all the way IN and back it out until your reticle and sight picture are focused and clear. A magnifier behind a Prism sight can be fiddly to get adjusted (lots of lenses to align and adjust), but his combo works like a charm.

Amazing clarity

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The clarity on this magnifier is better than on the SLx 3-18x50mm FFP ACSS Athena BPR MIL, it's crazy to get this performance out of a magnifier. There's true edge to edge clarity. This optic is also using proper thread inserts instead of helicoils.




Excellent magnifier!

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Picked this up with the reccomended flip to side mount to pair with the PA micro prism 1x. I was skeptical of it would work with a prism, but after mounting it and finding the right combinations of adjustments on both the magnifier and micro prism, I got the reticle and magnified image to come in very clear! I love it and couldn't be happier especially for the price. Glass quality is great and the overall feel, fit, and finish is top notch. Will be buying more of these for other ar's in the future!

Excellent value

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Marshall recommended this over the LER 3x I had been waiting to come back in stock. He was right. I have it magnifying my Gen 2 prism. Glad I went this route. I needed the small spacer for the slx gen 2 scope.

No mounting hardware included


This magnifier looks great. Whenever I ordered it in January of ‘22 there was no information on the page offering ways for it to be mounted or to even purchase ways of mounting it. Only after paying and receiving the magnifier I was informed that I had no way to mount it or no way to purchase a way to mount it. Leaving me this great looking magnifier I can’t use. I don’t want to give it a low rating review because I think it’s better than that. I just think PA needs to make future customers aware that what they are paying for isn’t going to be what they’re going to get.

Pretty legit

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Just got put around 90 rounds using it already the glass quality is great, and it's easy to center the red dot. I think for the money you'd be hard pressed to beat, and maybe cant beat it.

Best yet.


Over the years, I’ve purchased a total of seven different PA optics, including scopes, prism optics, red dots, and magnifiers. Today, I received this little guy. Right out of the box, I could tell what a huge improvement it is over the older model. With this magnifier, I also purchased the PA flip to side mount. I paired it with an EOTECH 512, which was with the old style magnifier. With no riser, it was the perfect height for the EOTech. After mounting and turning on the EOTech, I found the reticle already perfectly centered in the magnifier. The glass is incredible for such a low price point with edge to edge clarity, with the only draw back of a slightly unforgiving eye box; but that’s understandable due to the small size of the optic. The mount is also outstanding, and I’m surprised with how robust it is. It’s the right amount of stiffness, and any movement must be intentional.
All in, an awesome optic and probably the best PA product I’ve owned so far.

Excellent 3X mag

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Very clear and works well behind Micro Prisms, once dialed in. I have Vortex 3x micro models and this glass is more clear at a much better price point even with having to purchase the mount. The new PA flip mount is great as well.

Better than the PA LER 3x

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Got this magnifier as a replacement for my PA LER 3x. Comparing the two, the glass on the SLx 3x is much clearer and it’s an absolute steal at the price point. The only negative for me (and reason for minus 1 star) is this optic is not compatible with the Unity Tactical FTC Omni mount. The footprint is the same but the housing is about 1mm too big to work. If primary arms reworks the housing (and perhaps drops in their inverted Pegasus ranging reticle), the SLx 3x would be unmatched in the market.