Skeleton Key Locks: these are 5 Lever High Security Locks, to be used on External Doors (any door that leads to the outside of a building). The difference between 5 Lever and 3 Lever Locks is the number of different Key combinations available. 5 Lever locks also have an 'anti pick' curtain (makes it harder to access the working components in the lock once fitted inside your door) and reinforced steel pins through the locking bolt. They are suitable with any of our door furniture that says 'Lock' In the description. These locks are supplied with a 'skeleton' key. 5 Lever locks have the same level of Security as Euro Locks. The main difference is that the 3 and 5 Lever locks are more 'Traditional' for Period Homes. These locks can be supplied keyed alike. Rebated Locks: these are used when you have one door closing into another door, also referred to as 'French Doors' (as opposed to a door in a 'Standard' door frame). Tradco Hardware's Rebated locks have a 13mm rebate in the face plate and striker.