The Asec deadlocking nightlatch for doors with narrow stile's (eg glass panel doors) operates in the same way as a standard nightlatch. However in this one, you operate the cylinder from the outside in the opposite direction. It locks off the internal handle thus stopping a thief from breaking the glass and gaining entry to the property. On external doors it should be used in conjunction with a British Standard mortice lock. Care must be taken to ensure building occupants are aware of this deadlocking feature and thought must be given to granting another form of exit in an emergency. The bolt may be held in the locked or in the withdrawn position by operating the snib. Suitable for timber & glass panel doors.