Bridgeport NIP-100600 Rigid Conduit Steel Threaded Nipple 1″ X 6″
https://nsiindustries.com/product/bridgeport-nip-100600-rigid-conduit-steel-threaded-nipple-1-x-6/
The Bridgeport 1″ Steel Conduit Nipple serves as a short raceway between two enclosures or boxes.