This light door closer is made of commercial-grade aluminum alloy, spring operation, totally automatic closing. Choose your return close speed to suit the environment in which the closer is placed by adjusting the hexagon socket head screw at the top. The parallel arm bracket can be folded up when its not in use. Suitable For Fire Doors, adjustable work with all types of medium doors, right and left opened doors, wood or metal doors, residential and commercial doors, exterior/interior door closer