The metal bolts that are attached to the hinge side ( hinge side ) of the door in the narrow side of the door leaf and, when closed, engage in holes in the anchor plate on the frame (door frame) are referred to as rear hooks (or partly also as lift-out protection, door hinge protection, rear gripping hook ).
Rear hooks prevent the door from being forced open on the hinge side or from being lifted out of the hinges (so-called anti-lift device). They are also used on fire and smoke protection doors to counteract any deformation of the door leaf in the event of a fire. They are usually used in pairs (for example under the upper and lower door hinge), for fire and smoke protection doors at the thirds or half of the door leaf height. In the case of doors with a wooden frame, rear hooks only offer burglary protection if the anchor plate is firmly anchored in the masonry behind the wooden frame (door frame) and the frame is backed with a pressure-resistant lining.