The Kinetic Research Group L2 Rail is a metal Picatinny Rail with Magpul MOE L2 hole spacing (1.190"). Mounts on various points of Whiskey-3 Chassis forend (side and bottom), the bottom of the X-ray chassis at the front, and the KRG Spigot Mount on the sides and bottom. Fits: Whiskey-3 Chassis forend and buttstock, X-ray buttstock