KeyMod is a pretty nifty interface system for firearm accessory components that is an attempt to set up a system even better than the MIL-STD-1913 rails currently in use. VLTOR Weapon Systems of Tucson, Arizona, first came up with the idea, and released it through Noveske Rifelworks of Grants Pass, Oregon. Since then, the KeyMod specification has been published in the public domain for adoption by the firearms accessory industry as a whole.
This design is comprised of two parts, the KeyMod slot and the KeyMod nut. The slot has a larger diameter through-hold combined with a narrow slot, chamfered on the backside while the through hole is big enough to allow the clearance of a quick-detach sling swivel (about 3/8” diameter).
The KeyMod nut is stepped, and the larger diameter end is chamfered 270 degrees around its diameter. This angled face interfaces with the chamfer on the backside of the KeyMod slot, allowing the accessory to slide and lock into place.
The KeyMod system is intended as a way to directly attach firearm accessories like flash light mounts, laser modules, sights, scope mounts, grips, rail panels, hand stops, and many other types of accessories.