... Taiwan area.3) We have imported stainless steel,piano wire,carbon steel,phosphor,bronze and so on. Extension spring ... closed coil design and hooked ends. MaterialPiano wire, stainless steel, High Carbon Steel, Nickel Plated, Phosphor copper Bronze, Copper Bronze, ... assist you figure out the load design.Style of Endshalf loop / full loopSurface FinishNickel / Zinc / Gold / Silver / Tin / Chromium / ...