Provides a number of critical functions such as preventing gas tank fumes from leaving the tank as well as protecting the fuel from outside contamination and maintains the appropriate pressure in the fuel tank. Many fuel tanks are designed to use a vented fuel cap to prevent a vacuum from forming in the fuel line. If fuel is leaking from the cap, a properly fitted replacement cap can solve the problem.Features a tether so it wont get lost or misplaced,Briggs and Stratton genuine parts are specially designed to exact OEM standards,Manufactured and tested to help deliver optimum performance in Briggs and Stratton engines