Spring Loaded Butterfly Toggle Anchor Set Standard Hollow Wall Fastener with Steel Screws for Drywall Plasterboard Product Description The Spring-Loaded Butterfly Toggle Anchor is a standard hollow wall fastening solution featuring spring-actuated wings that fold flat for insertion through a pre-drilled hole and automatically spring open behind the wall surface. The butterfly wing design creates a large load-bearing contact area against the back of drywall or plasterboard