This is a genuine OEM sourced replacement primer bulb, not an aftermarket equivalent. It is commonly utilized on Kawasaki engines installed on Toro lawn mowers. This purpose of the purge bulb is to force the fuel from the tank into the carburetor. Once the carburetor is full of fuel, the excess fuel will be purged back into the tank in th...Read moree fuel return line. This item consists of black plastic base and the flexible clear plastic bulb. Over time it may deteriorate and crack requiring replacement.