Locksmith Reserved Mortise cylinders are our ENTRY LEVEL restricted keyway. These cylinders are used to replace cylinders that may be missing or not functioning. These cylinders provide a higher level of security as they are reserved for locksmiths only. They are commonly used to change from a common keyway to a more restricted keyway. When you do not want your employees to make an unauthorized duplicate key, heses cylinders are the ones for you. custom keying available at an additional charge