This is a Blusmart bike lock which has a 5 digit padlock on it. The five digit padlock is much more secure than the usual four digit one and more convenient than having to carry a key. It is attached to a 180cm heavy duty chain which is 12mm thick. This means that it is really cut resistant. It has an outer covering of rubber which means that there is no risk that the chain will scratch your bike or cause any other sort of damage. It comes with a mount for your bike so it can always be with you and you will always be able to lock your bike up securely when you need to leave it behind.