Medeco Mortise cylinders have threads on the outside of the shell and are designed to be screwed into other manufacturer's mortise lock cases. A cam on the back of the cylinder operates the lock mechanism and a set screw holds the mortise cylinder in place. Medeco Rim cylinders are used with auxiliary rim locks such as: surface mounted deadbolts, night latches, panic devices and jimmyproof locks (also know as vertical dropbolts or interlocking deadbolts).