Real Avid Master-Fit Wrench, Wrench, Stainless Steel, 30mm Free-Float Barrel Nut AVMF30BNW Master-Fit 1/2" Crowfoot Wrenches are purpose built and specialized for precise fitment to minimize marring on gun parts. Constructed of titanium coated stainless steel" delivering the highest level of precision to confidently apply torque to AR platform.