Garvin RC-300 3 Inch Galvanized Rigid Threaded Coupling (Rc-
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
Supply Giant NDUU0534 3-1/2" Straight Merchant Steel Coupling With Black Coating - Amazon.com
RELIABILT 2-in Galvanized Coupling in the Galvanized Pipe & Fittings department at Lowes.com
Amazon.com: FangKingNo 10pcs 1/2" to 3/4" PVC Reducing Female to Female Threaded Coupling for PVC PIPE Pressure Fittings ,PVC Reducer Female Adapter for PVC PIPE Connector White (1/2 Inch to 3/4 Inch) :