Throttle control Valve. This is commonly known as a "Bullwhip" and is produced by Conrader Valves and is made in the United States. This valve controls the engine throttle speed on gas-powered air compressors when used in conjunction with a pilot/unloader valve. This valve is compatible for Subaru brand small engines 9 hp or smaller portable compressors. This is mounted next to the throttle control on the engine and a air line is used from the pilot valve to control the engine speed using this valve. Specifications: Control Rod Length: 3.5" ( Can be cut down) Overall Length: 6.25" Valve Inlet Thread Size: 1/4" compression Compatible with Subaru Engines Up To 9 Horsepower To make sure this will fit your current compressor compare our pictures to your current valve. If they look the same and the engine hp is less than 9 hp then it should mount right up.