The Geissele Super Modular Rail MK18 (brand part number 05-791B) is a 16.5-inch black M-LOK handguard purpose-built to interface with the Arca-Swiss Quick Release system, making it a favorite among competition shooters who move between multiple mounting points in a stage. Based on the MK16 M-LOK Super Modular Rail, it keeps a small diameter and low overall height for a slim, fast-handling profile. The flat base features an Arca-style 35mm dovetail at 45 degrees, letting the rail slide into any position along an Arca-Swiss mounting base for quick repositioning. It uses Geissele’s proprietary 2.25-inch barrel nut for a straight, true fit along the entire length of the free-float rail, and it is 3D precision machined from 7000 series aluminum for a strong yet lightweight build.

Key Specifications

• Length is 16.5 inches, suited to mid-length and rifle-length gas system builds.
• Mounting system is M-LOK for attaching lights, grips, and other accessories.
• Base is Arca-Swiss compatible, with a 35mm dovetail at a 45-degree angle for quick-release mounting.
• Barrel nut is Geissele’s proprietary 2.25-inch design, keeping the rail straight and true along its full length.
• Material is 7000 series aluminum, 3D precision machined for strength with minimal added weight.
• Finish is black.

Frequently Asked Questions

What does the Arca-Swiss compatible base do? It lets the rail mount to any Arca-Swiss quick-release base and slide into position, useful for competition shooters who reposition often.

What barrel nut does it use? It uses Geissele’s proprietary 2.25-inch barrel nut for a straight, true fit.

What mounting system does the handguard use? It uses M-LOK for attaching accessories.

Buy the Geissele Super Modular Rail MK18

Get a slim, Arca-ready handguard built for fast repositioning on the clock. Shop more Geissele Automatics rails in our AR handguards selection, and order this handguard from our Lubbock, Texas gun shop.