A jack nut is a specialized threaded insert designed for thin, soft, or brittle materials like sheet metal, plastic, or fiberglass. As a screw is threaded into it and tightened, the slotted body collapses and flares outward on the blind side, forming wide legs that distribute the clamp load over a large area. This prevents the fastener from pulling through the substrate.
Heard on the job
The plastic panel is too thin to tap, so install a jack nut before you mount the bracket.