Door Automatic Closer Sensor Door Closer 65Mn Tension Extension Spring Sliding Door Spring 2Pcs Name: Automatic Close Door Spring Materials: 65Mn Surface Treatment:Untreated Suitable for 80-120 cm vast heavy doorways Light doors: Screen door cabinet door toilet door etc. Household doors: Wooden door workplace door aluminum alloy door etc. Heavy doors: Security door solid door iron door etc. Product Feature: 1.Easy to put in and use. 2.Made of 65Mn, by no means rust, durable 3.strong pulling force, hard to break.