Dedicated wrench has four precision-machined teeth that ensure full, non-slip engagement of all four notches in an M4-type receiver extension nut for easy removal and installation of collapsible carbine buttstocks. Transfers all the torquing force to the nut for fast tightening or removal without risk of damage to nut, extension tube, or receiver caused by the wrench slipping. Includes the handy add-on features of our universal M4 buttstock tool: pry blade/screwdriver, " square torque drive opening, fixed stock receiver extension remover, and a convenient hole in the handle for hanging the wrench on a pegboard. Heavy duty steel construction, machined from a single piece of .312" thick steel Mfg: Brownells SPECS: Steel, hardened, black oxide finish. 7-1⁄8" (18.1cm) long. Fits current-model M4-type receiver extension nuts with four square notches.