GREAT COMPATIBILITY: This brake return spring tool fit for large trucks and trailers with air brakes with S cam design. Use for install and remove return springs on commercial truck and trailer. WIDE APPLICATION: The Spring Tech Tool compatible with s-cam return spring. If is s-cam brake type, the Truck Brake Spring Tool works on the return spring install/uninstall. EXCELLENT FUNCTION: Provides leverage to back out brake shoe and remove roller cam. The tool can cups the return spring to prevent it from sliding off and possible injury. The end with unique slight bend design to make it fit better and not slip as easily. .