The outer diameter specification is 1.6-60mm, and the thickness is 2.2-8.8mm. It can be made of iron, stainless steel, medium carbon steel, copper, aluminum, plastic, nylon and so on. The surface treatment of Trivalent Chromium Color zinc, trivalent chromium blue white trivalent chromium zinc, black zinc, white zinc, nickel chromium green, black nickel, chromium, Dacromet, geomet, tin, blackening treatment etc..