Model 14, 24, 34 Fail-locked 14The door can only be opened while a contact is made. In alternating current operation, a humming noise is audible. In direct current operation, there is no noise. When mounting with a throw-open... Hold-open function 24The latch bolt controlled locking pin in the centre of the electric strike latch keeps the electric strike unlocked until the door is opened, even after contact has been made. Fail-unlocked 34The electric strike is locked for as long as the power is on. If the power is switched off or if there is a power cut, the electric strike latch can be moved and the door can be opened.