Deadlocking Rim Cylinder Nightlatch 40mmDeadlocking Rim Cylinder Nightlatch 40mm, c w matching finish cylinder and 3 keys. A robust nightlatch providing a complete security solution for internal or external doors. The slide snib function allows the latch bolt to remain retracted permitting the door to remain unlocked if required. Comes with a 5 year mechanical guarantee and is Fire Door rated. Suitable for use in domestic, and commercial environments.