There are a number of conditions where a security seals should be used instead of a lock.  All locks with the possible exception of high security locking systems can usually be surreptitiously (using picking and bypassing) or forcibly defeated (with readily available hand tools) very quickly. Replacement locks are easily obtainable and can be used to replace the removed lock. Lock failure would normally be blamed unless an examination was performed on the suspect lock. Locks do not normally have serial numbers or unique identifying marks. . Locks often require complicated and expensive key-control programs. Usually, the key or combination must be available at the receiving location. This can create vulnerability through compromise of the key or combination in route. Seals are typically easier and faster to remove than locks. This can improve operations and is particularly important in emergencies. Seals are usually lighter and smaller than locks, which can be particularly important for air cargo shipments and courier packages.