Horiznext npt 1/2 (means the inner diameter of the thread is 3/4 inch) cast female taper threaded pipe coupling, stainless steel 304 coupler for mush tun cooler and shower hose, 2 pcs - Amazon.com
External Coupling, 2 in For Pipe Size, Structural Pipe Fitting - 30LW92|30LW92 - Grainger
RELIABILT 2-in Black Coupling in the Black Pipe & Fittings department at Lowes.com
RELIABILT 3/4-in Black Coupling in the Black Pipe & Fittings department at Lowes.com
2 1/4” 2.25" ID to 2 1/4” ID Universal Exhaust Pipe to Pipe Coupling Connector | eBay