S&S Compression Release Kit Features: Consists of a small valve that opens during starting that allows a portion of the cylinder pressure to escape into the exhaust port of the cylinder head Reduced cylinder pressure makes it easier to turn engine When engine starts, valve closes and engine runs normally, with full compression Solenoid operated Electric compression releases open when you press the start button and close when the button is released Manual compression releases are opened manually and close when the motor starts Require use of S&S Cycle die-cast Twin Cam style rocker covers (or similar) with a central hole or chimney when installed on Ssw+ or Twin Cam style S&S Cycle engine Chimneys required to provide clearance for solenoids Compatible with S&S Cycle rocker boxes or Evolution engines