Insulated Bushing, 4″, Zinc Die Cast to Protect Conductors
https://dev.nsiindustries.com/product/insulated-bushing-4-zinc-die-cast-to-protect-conductors/
The Bridgeport 4″ Zinc Die Cast Insulated Bushing can terminate threaded rigid or IMC to a box using a simple locknut. It features a plastic metaliner that prevents damage to wire insulation.