Hilitchi 410-Pcs High Quality Stainless Steel Spring Lock Washers Assortment Kit Specifications - Washer Type: Spring Lock Washers - Sizes: M2 M2.5 M3 M4 M5 M6 M8 M10 - Material: 304 Stainless Steel Features - Made of 304 stainless steel material, very good corrosion resistance.