... steel flat spiral spring 2.fully-automatic spring production Black steel constant force Flat spiral spring Flat spiral coil ... mild steel wire, manganese steel wire, phosphorus copper wire, nickel-plated wire, zinc-plated wire, tin-plated copper wire, nickel-plated steel wire, non-magnetic ... gold, silver, white, red yellow, blue, green, purple, black, etc., salt spray test more than 100 H. Appearance ...