Custom China High Quality Factory Price Garage Door Torsion spring /Roller Door Spring/Roll -up door spring For Automatic Door/ Roller Shutter DoorSPECIFICATION :
MaterialHigh carbon steel :77B /82B/Zinc spring steel /SS SPRING STEELWire diameter 5mm,5.5mm,6mm,6.5mm, 7mm, 7.5mm ,8mm ,8.5mm ,9mm, 9.5mm ,10mm, 10.5mm , 11mm 11.5mmInside diameter 50.8mm -152mmFree length 325-3500mmSurface Oiled Tempered /Black Coated /Corrosion resistant/ZincWinding hand Left and rightUsageRolling Door /Garage door/shutter door/Industrial