Drywall Toggle Bolt (Butterfly Anchor)
Direct Answer
The Toggle Bolt (Butterfly Anchor / Spring Toggle) is a two-piece hollow cavity anchor consisting of a long machine screw threaded through a spring-loaded dual-winged metal crossbar. When pushed through a pre-drilled wall hole, the wings snap open inside the hollow wall cavity, distributing heavy pull-out tension across the rear face of drywall, plaster, or hollow cinder block.
Source: Federal Specification FF-B-588D / ASTM Standards
Specs
| Assembly Components | Truss-head / round-head machine screw (typically 1/8", 3/16", 1/4", 3/8" or M4, M5, M6, M8) + spring toggle wings |
| Required Clearance Hole | Large borehole required to pass folded wings (e.g. 1/4" toggle requires 5/8" [16 mm] hole) |
| Substrate Compatibility | Drywall (1/2" & 5/8"), lath & plaster, hollow concrete masonry blocks (CMU), ceiling drywall |
| Working Mechanism | Spring-loaded carbon steel wings snap open to 180° perpendicular clamp bar behind wall |
| Safe Working Tension Load (1/2" Drywall) | 1/4" Toggle: ~50–90 lbs (22–40 kg) tension / ~100–150 lbs (45–68 kg) shear |
| Single-Use Disassembly Warning | If screw is fully removed, the toggle wings fall permanently down inside the wall cavity |
The Heavy Hollow Wall Champion
Because gypsum drywall has low tensile core strength, standard expanding plugs pull straight out under heavy tension. Toggle bolts bypass drywall weakness by clamping a wide 2-inch solid steel bar against the solid paper/fiber backing of the sheetrock, making them the safest choice for heavy ceiling fans, hanging plants, floating wall cabinets, and articulated TV wall mounts on hollow stud bays.
Installation Sequencing Rule
Unlike modern sleeve anchors, the machine screw must pass through the fixture bracket BEFORE the toggle wings are threaded onto the screw. Once pushed into the wall and tightened, unscrewing the bolt completely releases the wings, which fall into the wall cavity.