Master-Fit single purpose crowfoot wrenches are made specifically for the job. Specialized for precise fitment and manipulation of A2 barrel nuts, buttstocks, muzzle devises 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.