Need a strong fixing in plasterboard or another hollow wall? These DIYUK molly bolts are heavy duty hollow wall anchors, also known as metal cavity wall fixings, hollow wall fixings, plasterboard fixings and metal plasterboard wall plugs, for plasterboard, drywall, gypsum board, particleboard, plywood and laminate panels. This pack contains 2 M4 x 39mm anchors, each with its own fixing screw.How they work: push or gently tap the molly bolt into a drilled hole until the flange sits flush, then turn the screw. The slotted steel sleeve flares open behind the board and spreads the load across its back face, while spikes under the flange grip the board so the anchor does not spin as you tighten. Fits with a screwdriver; no specialised tools required.The fixing screw is removable and reusable: take it out, position your fixture and screw it back in, and later take the fixture down or swap it without the anchor dropping into the cavity. Carbon steel with a white zinc-plated finish gives everyday corrosion resistance, and durable materials give a long lifespan.Specification:Size: M4 x 39mmThread: M4Sleeve diameter (D): 6.5mm (0.26in)Sleeve length below flange (L): 39.0mm (1.54in)Overall length including screw (l): 49.0mm (1.93in)Weight per anchor: 8gMaterial: carbon steel, white zinc-platedPack size: 2Choosing a size: pick the thread (M4, M5 or M6) to suit your fixture, then check your board thickness against the sleeve length. The hole must let the sleeve pass through: 6.5mm for this size.Typical uses: shelving and brackets; kitchen, bathroom and mirror cabinets; TV brackets and media units; radiators and towel rails; curtain poles and blinds; handrails and grab rails; metal frameworks, railings, barriers and stair fittings; pipes, ventilation ducts and other building installations; brackets, hangers and mounting elements on walls and ceilings.Seven sizes from M4 x 32mm to M6 x 53mm, in packs of 2, 5, 10, 20 and 50.