Introducing the F.W.E Chain Checker. Keeping an eye on how your chain is wearing is vital as it can save you purchasing a whole new drive train. The more that your chain stretches the quicker it wears down the teeth on your cassette and front chain rings. Therefore keeping up to date with your chains wear is can mean spending money on a new chain or spending hundreds on a whole new drivetrain. Make sure you are on top of your chains wear with the F.W.E Chain Checker.