You can use it either in a chain cleaning device like the X-3 Dirty Chain Machine, or spray it directly onto the cassette and chain. When you are spraying it onto the equipment, leave it for a minute or two before you start scrubbing the big bits off. Pretty quickly you'll see how completely this formula cuts through the grease and grime and caked-on dust. It will be so effective and safe for the environment, you'll wonder how well it would work on your dishes. Just kidding. Don't even think of that. This is not to be swallowed or ingested in any way, and does advise you wear gloves or some sort of protection on your hands because certain skin types may find it irritating. However, it will remove everything from chain oil and wax residue to tree bits and winter road spray. If you are racing 'cross or constantly riding in appalling conditions, then investing in the Drivetrain Cleaner will make every clean-up job that much faster, easier, and more effective.