Neat Idea for M-LOK & KeyMod Rails – Slim Picatinny Adapters by Arisaka Defense

I have rather enjoyed watching M-LOK & KeyMod proliferate throughout the market with the various accessory manufacturers embracing the specification. The specs, while fantastic, do have potential issues with purely round or octagonal handguard systems. Simply put, those types of handguards often have to have an OD of a certain size to clear barrel nuts and suppressors which can make mounting forward iron sights rather awkward.


The OD of the handguard coupled with common adapters are typically too tall. The rail will sit about 1/8″ to 1/4″ taller than the base receiver, which makes matching irons a pain or when mounting accessories to the 12 o’clock position, sit tall which can interfere with optics and sight picture.

To the relief of geardo’s like me, Arisaka Defense has stepped in with slim rail adapters for both the M-LOK and KeyMod systems. The adapters feature five complete picatinny rails (ideal for folded BUIS) mounting via three M-LOK t-nuts or three “keys” for KeyMod.


Weight is kept to a minimum, with only .7 ounces of 6061 aluminum for the M-LOK version and .6 ounces for the KeyMod version. Both are type III hard-coat anodized and arrive with mounting hardware installed.

Pricing for both is set at $28.00 retail available directly from Arisaka Defense and their dealer network. 


Nathan S

One of TFB’s resident Jarheads, Nathan now works within the firearms industry. A consecutive Marine rifle and pistol expert, he enjoys local 3-gun, NFA, gunsmithing, MSR’s, & high-speed gear. Nathan has traveled to over 30 countries working with US DoD & foreign MoDs.

The above post is my opinion and does not reflect the views of any company or organization.


  • Risky

    I don’t understand why no one makes a simple direct mount M-Lok or Keymod front sight yet. Isn’t the point of the platforms to eliminate the rail systems?

    • ExMachina1

      Maybe because an AR hand guard w/o a rail on top is already limiting? Rails for optics are still the most secure and universal mounting option. Personally, I would not even consider a handguard that didn’t have a rail on top.

      • Ebby123

        I think there are some advantages for the PDW/ Subgun platform, where being as small/slim/snag-free as possible is a significant advantage – but otherwise I agree.

    • Sianmink

      Yeah if I am using a handguard without a top rail, it’s pretty much 100% because there’s a front sight on the gas block.

      This could be good for lowering the profile of a light or laser mounted topside though.

  • jtx

    So awesome if you like accessories to fall or get bumped off your gun

    • Bronson

      Why would they fall or get bumped off of the gun?

    • Ebby123

      I think this is internet mythology.
      When properly installed, I have never had Mlok or Keymod come loose one me. If you installed a pic-rail accesory and didn’t tighten down the screw, you’d have the same result.

  • Harry’s Holsters

    Great for the price point but doesn’t hold a candle to the KDG mounts for my purposes.

    • Ebby123

      Why? Serious question.

      • Harry’s Holsters

        Because any rail on an MLok hand guard besides the 12 rail doesn’t make sense to me. The KDG mounts are easy on off. If I have the option I’ll avoid 1913 all together be anything besides sighting systems.

  • Phillip Cooper

    So let’s see here… we put an adapter on an adapter in order to adapt a (flashlight/LTD/laser/WTFE) to our weapon?

    What question does this answer that Picatinny didn’t already have well sorted?

    • Jack

      Unnecessary bulk and weight.

      Next question.

      • Ebby123

        Mostly bulk. Why make a gun fatter or taller than it needs to be?
        Especially when most of us only use the bottom rail, and a small section of the top one.

        • Jack

          I stand by my bulk AND weight. Take a comparable length handguard, quad vs m-lok/kmod, and how much lighter is the m-lok/kmod? A monolithic upper that was previously quad rail, went to keymod and saved approx a half pound of the weight of the rifle. AND it was slimmer….. But mostly lighter.

    • Bill

      I’m sorta in the same boat. OK, a Pic quad rail is a cheese grater, but somehow I’ve survived, all my stuff is readily cross-compatible across all my guns and I don’t have an excess of adapters and stuff. I might try one of the other systems for the heck of it, but i’m invested heavily enough in the 1913 standard that I doubt i’d want to start buying different accessories that were KeyMod/MLOK specific.

      I’ll never be one of the cool kids.

      • Jack

        If quad rails work for you… Awesome!! Nobody has to buy this stuff. But there’s clearly a market for m-lok/kmod offerings. There’s a lot of hate in the few comments here, (not you in particular Bill) mostly based on opinions, some on the lack of being able to tighten a fastner appropriately.

  • roguetechie

    Please tell me at least someone else was hoping that the product was named the SLIM PICkins