... alloy steel, iron plated Black color bending spring1.bending spring with wire diameter 2.made of carbon steel, piano steel ... factory,Products have got the certification of UL,FCC,VDE,GS,CE,our factory follows "honest style,high-quality,reasonable ... , piano steel, alloy steel, iron plated steel.3. bending spring is extensively used in telecommunication, computer peripherals, housing appliance, switching ...