Size: We contain 500 pieces in the most popular and popular sizes: 100 pieces M2 x 5 x 1 (model x outer diameter x thickness), 100 pieces M3 x 6 x 1, 50 pieces M4 x 8 x 1, 50 pieces M5 x 10 x 1, 50 pieces M6 pieces M6 pieces M6 x 12 pieces . 1,2, 4. 0 M8x16x1.4 screws, 10x M10x20mm screws. Nylon Gasket: These black flat washers are made of soft and durable nylon, good insulation and corrosion resistance, lightweight. These round washers are widely used in household appliances, electric switchboards, sewer pipes, faucets, etc., pipes, generators, semiconductors, automobiles, ships and industrial fields. Function: The round spacer washer can be applied to disperse the pressure from the bearing surface of the fastener such as bolts to protect the surface of the connected part. In addition, it can reduce friction, prevent leakage, insulate, prevent loosening, etc. This rust-proof nylon flat washer assortment is easy to carry with a storage box, lightweight and size different, great for DIY lovers, please make sure which size you want.