This check valve or the fuel tank vent is connected to the fuel tank in the following products: hedge trimmer, leaf blower/vacuum, chainsaw, edger, engine, tiler, auger, water pump, chipper shredder, sprayer, and brush cutter. The check valve allows air into the fuel tank to prevent vacuum when the fuel is being fed through the fuel line. Tip: if the vent is clogged, your engine may stall. Usually, the vent line is connected to a fuel grommet that is installed on the fuel tank. The tools needed for this installation are: needle-nose pliers and a small slotted screwdriver. Remember to wear work gloves to protect hands. Refer to the manual for an accurate repair guide.