Toggle Bolts are a two-part assembled unit, including a machine screw and a spring wing toggle nut. Toggle bolts have various trade names including butterfly anchor or hollow wall anchors. You might use a toggle bolt for projects requiring fastening to a hollow wall, or into drywall. Installation requires the wing toggle nut to be on the far side of the wall so that the bolt can be tightened into it. When removing the bolt, the wing toggle nut will fall behind the wall which is why we also offer toggle wing nuts to be purchased separately if you need.