Commercial Electric 1 in. Rigid Metal Conduit (RMC) Threaded Coupling FRPTS-100-1 - The Home Depot
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
PVC Schedule 40 FPT x FPT Threaded Coupling, 3/4" x 3/4"