The Oxford LidLock is small enough to fit in your pocket or under your bike seat and comes with a T bar to fit through your helmet ratchet - in case your helmet doesn't have a loop the lock can go through. The lock looks like its made out of aluminium so wouldn't take much to break it however it is a deterent factor. The plastic covered wire is long enough to fit around your handle bars in case there is nowhere to attach the lock. To set the combination - press in and turn the end of the lock 90 degrees while open. There were no instructions so it took a few minutes to work this out.