Steel, usded to lock the wheels when parking . Name :Wheel lock , Wheel clamp, Wheel klamp,Tyre lock Model :CAS-CLS-6 Name :Wheel lock , Wheel clamp, Wheel klamp,Tyre lockModel :CAS-CLS-6Material : high quality steel pipe, high pressure .Function :Lock the wheel of the cars . It can be used in parking lots and any other places for car stopping . Steel Wheel Lock