Rigid or IMC Conduit Threaded Aluminum Entrance Cap 6″
https://nsiindustries.com/product/rigid-or-imc-conduit-threaded-aluminum-entrance-cap-6/
The Bridgeport 6″ Rigid or IMC Conduit Threaded Aluminum Entrance Cap serves as a connection point for service entrance wires. This threaded type entrance cap features two holes with 1-1/8″ diameter or four holes with 1-3/4″ diameter.