Hiplok Chain Lock The locking mechanism uses a disc tumbler system which is almost impossible to pick (as opposed to a pin tumbler mech which can be bumped or picked quickly) the main padlock uses a hardened shackle which is resistant to bolt croppers and hacksaw attacks The locking mechanism uses a disc tumbler system which is almost impossible to pick (as opposed to a pin tumbler mech which can be bumped or picked quickly) the main padlock uses a hardened shackle which is resistant to bolt croppers and hacksaw attacks No.VALUE No.VALUE