... chain spring/strong forged steel link chain for slings Specification1.made of carbon steel,stainless steel, manganese steel wire, nickel wire ... of charge 5.advanced CNC spring machinery, grinding and shot peening machinery,Precise tensile strength ... peripherals etcCertificatesISO9001,RoHS Equipments Advanced CNC spring machinery, grinding and shot peening machinery,Precise tensile strength testers ...