20 PCS Free Float Nut Washers thin Shims Alignment for 223 , 5.56
These are .004″ thick for very fine adjustments. Made from high quality stainless steel. The Nut Washers for .223Thickness: 0.004″Dimensions:OD: 1.192″ / 30.0mmID: 1″ / 25.0mm Will fit .223,7.62×39,Blackout AAC 300