Real Avid Master -Fit 13 Piece Crowfoot Wrench Set Gray/Red AR-Platform Heavy Duty Torque Wrench Handle 13 Pieces MASTER GRADE A2/AR15 WRENCHES & TORQUE WRENCH: Master-Fit single purpose crowfoot wrenches are made specifically for the job. Specialized for precise fitment and manipulation of A2 barrel nuts, buttstocks, muzzle devices and castle nuts. Titanium coated stainless steel construction provide tight tolerances for solid nut gripping strength and enhanced no-slip fitment. Paired with the heavy-duty Master-Fit Torque Wrench it takes Gun DIY building to a new level of Master Grade quality and precision.