Toggle wings are light-duty anchors used with machine screws in hollow block or drywall board. The user drives the machine screw through the hole at the center of the spring-loaded toggle wings, which then folds for installation through a predrilled hole. Once through the hole, the wings re-open on the other side of the hollow block or drywall board.  With the machine screw attached, toggle wings are often called toggle bolts. The machine screw is sold separately.