Mechforce Variable Timing Crush Washers for Muzzle Device Alignment Includes (4) crush washers with four different thicknesses each offsets un-torqued part with 90 degree increment One of these washer is guaranteed to deliver the right orientation positioning with the correct torque value regardless of the female thread and male thread manufacturers Crush Washers are made from special engineered, heat treated mill-spec steel that has been fine turned balanced between high spring rate and ductility to meet the function requirement of "crushed with high spring tension without cracking". black phosphate surface treatment for corrosion resistant Detailed installation manual included. MADE IN USA.