Tacfire's combo wrench serves both the 5.56 and .308 AR platforms in one convenient, easy to use tool. This wrench aids in the assembly, tightening, or removal of barrel nuts, muzzle brakes, barrel extensions, castle nuts, delta ring assemblies, and hex bolts/screws. Uniquely designed, it offers extreme versatility as it features the ability to build, service, and maintain both your 5.56 AR-15 and .308 AR-10 rifles.