The Muc-Off Bio Drivetrain Cleaner is an environmentally friendly product that gets your bike functioning like new again. This formula simply sprays onto your cassette, chain, and crank and eats through mud and grease. Simply spray the cleaner onto your drivetrain, agitate with a brush if needed, and leave it for a minute. Then rinse it off and youre good to go. This drivetrain cleaner is fully biodegradable so it can be used outside to get your drivetrain looking new again.