3-Piece Conduit Coupling, 4″, Iron for an Impact-Resistant Fit
https://nsiindustries.com/product/3-piece-conduit-coupling-4-iron-for-an-impact-resistant-fit/
The Bridgeport 4″ 3-Piece Malleable Iron Conduit Coupling joins two threaded rigid or IMC conduits for an impact-resistant fit.