Performance Tool W5217 110pc Copper Washer Assortment Sizes: 1/4" = 30pcs, 5/16" = 25pcs, 3/8" = 20pcs, 7/16" = 15pcs, 1/2"=10pcs, 5/8"=10pcs Copper, high conductivity, corrosion resistant High conductivity, corrosion resistant copper washer assortment, great for sump plugs, water, fuel and hydraulic fittings Perfect for electrical connections on household and commercial appliances, automotive and marine uses in which the power source has a threaded/bolt-type connection