Cuts off fuel in your carb to prevent “dieseling” and it works great. Fits in both 32/36 DGEV and 38/38mm DGES carb, will not fit the DGV (manual choke). It is a tight fit in the 38/38. Replaces the primary jet and stop the fuel when power is cut. Hooks up to an ignition hot that is powered whenever the vehicle is running.