50mm. The ADAMS RITE Lip Extension is to suit the Adams Rite 7400 Series Ultraline mortice releases. Lip extensions are designed for use with centre hung doors, thick doors, or other applications which may vary from the standard door which closes flush with the door jamb face. . To suit Adams Rite Ultraline 7400 Series Mortice Releases. For use with flat faceplates only. Measured from the edge of the frame to the centre of the release. Bolt-on fitting