Assembly/disassembly tool for removing the buffer tube, featuring three lugs that accurately engage the indents on the receiver extension nut (aka castle nut). This wrench is made from heavy gauge steel (not that flimsy crap) with a protected handle for comfortable use. This Carbine Wrench is so well built it will be the last one you ever buy. You'll need a carbine wrench to install our X-180 Sling Mount.