The Barrier lock is a 25mm armoured cable lock. It has braided steel cable which is protected by steel rollers.
The Oxford Barrier has a key replacement service. When you buy your Barrier, simply note down the number which comes attached to the keys on a metal tag. Keep this in a safe place, then in the event that you are unfortunate enough to lose all your keys, it will be possible to get a new key made up for you.