... zinc-plated, nickle- plated, chrom-plated, copper cover Model Number2mm-50mmApplicationtoy, anit-rust purposeShapeshperialMaterialsteelDimensions2mm-50mmChemical CompositionsteelCertificationISO9001Copper Plated ... zinc-plated, nickel plated, chrome plated and copper balls with size from 2mm to 25. ... , wheel, bicyclesand trust bearing pulleys Copper Plated Ball/zinc-plated, nickle- plated, chrom- ...