The latchbolt can be retained inside the lock case. Deadlocking is controlled by a snib in the front plate. Snib position: UP : Deadlocking, latchbolt protrudes 21 mm. The lock can be opened only with a key or a thumbturn. DOWN : Latchbolt is retained inside the lock case. The door is kept closed by using a door closer. 4195X is the microswitch version of the lock. The switch changes it's status when the latchbolt leaves its day locking position, i.e. the bolt protrudes 15 mm or more.