This listing is for a genuine OEM Rolair throttle/idle control assembly for gas-powered air compressors. The assembly connects to the throttle plate/carburetor of the engine to shift from idle to high speed and vice versa. The valve itself can attach to the engine throttle plate or thread into the pilot/unloader valve, and the air line or cable connects the two and actuates the throttle/governor on the engine at specific pressures to control the speed of the engine.