Description
The Arisaka Defense Indexer is a low profile finger stop made for the Geissele SMR 416 handguard. It sits between your index and middle fingers and gives the support hand a fixed spot to index to every time. It also works as a hand stop, a barricade rest, and a stop that keeps your fingers from creeping forward on a short rail. The key detail is fitment: this one bolts directly to the SMR 416’s own mounting pattern, not to M-LOK.
It is machined from 6061-T651 aluminum and hard coat anodized to MIL-A-8625 Type III. Arisaka specs it at 0.9 oz and 1.0 in. tall. In the box you get the Indexer and two 10-32×3/8 in. Torx flat head screws. You need an IP25 TorxPlus driver to install it, and that is not included. Made in the USA.
Heads up: Arisaka states this fits the older direct-mount Geissele SMR 416 handguards only. It does not fit the newer MK15 416 rails that have M-LOK slots. For those, use the M-LOK Indexer or the M-LOK Hand Stop instead.
Specs
- Material: 6061-T651 aluminum
- Finish: MIL-A-8625 Type III hard coat anodized, black
- Weight: 0.9 oz
- Dimensions: 2.2 in. long, 0.58 in. wide, 1.0 in. tall
- Fits: Geissele SMR 416 direct-mount handguards (not MK15 M-LOK)
- Includes: Indexer, two 10-32×3/8 in. Torx flat head screws
- Tool required: IP25 TorxPlus driver (not included)
- Made in: USA
Who it’s for
Shooters running an HK416 or MR556 with the original Geissele SMR 416 rail who want a consistent support hand index point without adding a bulky grip.
Who should skip it
If your rail has M-LOK slots, this will not bolt on. Get the Arisaka Hand Stop M-LOK we carry instead, which does the same job on any M-LOK handguard for less money.




