A hook bolt is a curved steel fastener similar to the top of a question mark. The straight section of the hook bolt is usually threaded and may have one or two nuts to be screwed on. Hook bolts are a type of anchor bolts that are commonly used to hang objects from ceilings and walls. Hook bolt fasteners are regularly bolted to the wooden stud behind the dry wall in order to increase the stability of the wall or ceiling. Standard washers and lock washers are usually applied to the joint between the hook bolt and the wall to prevent the bolt from loosening due to weight and vibration. Some hook bolts are designed to be screwed into bolt anchors, and the bolt anchors expand in the wall to lock the hooks in place.