Rigid, EMT or IMC Conduit Clamp-On Aluminum Entrance Cap 3″
https://nsiindustries.com/product/rigid-emt-or-imc-conduit-clamp-on-aluminum-entrance-cap-3/
The Bridgeport 3″ Rigid, EMT or IMC Conduit Clamp-On Aluminum Entrance Cap serves as a connection point for service entrance wires. This clamp-on type entrance cap features three 1-3/4″ dia holes or four 1-1/8″ dia holes.