Specification:Made of manganese steel material,with highly abrasion resistance,durable to use.Tension spring can be used in many occasions, such as production and assembly, experiment, research and development, maintenance,etc.The Extension Springs give resistance to a pulling force and become longer under load, applications include balance scales,garage doors,washing machines,oven door and applications which requiring various types of tension devices.Wire Diameter: 2.5mm/0.1"; Outer Diameter: 18mm/0.7"(OD); Free Length: 100mm/3.9"Package Content : 1 x Extension Spring.