E-Z Lock® AC/MC Locknut Connector 1/2″, Die Cast Zinc
https://dev.nsiindustries.com/product/e-z-lock-ac-mc-locknut-connector-1-2-die-cast-zinc/
Bridgeport snap-in locknut connectors offer superior installation speed with minimal tools required. Internal spring steel locking ring tabs securely clamp the cable in place. Then, a hand-tightened locknut secures the connector to the knockout.