Yale 89 Deadlocking Nightlatch - Brasslux - 60mm BacksetYale 89 Deadlocking Nightlatch Brasslux 60mm Backset The Yale P85 (40mm) & P89 (60mm) are deadlocking nightlatches suitable for left & right handed, and inward opening doors with a thickness of up to 57mm. The Yale 89 deadlocking standard nightlatch high security locks are widely used front door latches. It key operated from the outside and lever handle operated from the inside. The latch automatically deadlocks on closing the door and the snib