Model 118®, 128, 138 Fail-locked 118®The 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 128The 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 138With its diminutive dimensions of 66 mm x 16 mm x 25.5 mm, effeff's 118 electric strike is the smallest standard electric strike in the world.