torsion spring ISO9001:2008 Manufacture CNC spring machine torsion spring1.Certification:ISO9001:20082.Application:cars,electonic and leectric appliance,furniture,computer,light-fixture,stationery,jewelry,optical equipment,sports equipment,girts,and remote control,etc.3.Material:stainless steel,carbon steel,aluminum,iorn,copper,manganese,etc.4.Surface Treatment:zinc plating,nickel plating, ...