Camco® 39733 RhinoFLEXTM RV Sewer Hose Swivel Elbow Fitting.
Connecting to the dump station... it's a crappy job. Here's the way to take the blood, sweat and tears out of the process!
Built-in 4-way adapter makes it easy. Built-in gasket makes it odor-tight (thankfully) without the need for hose clamps. Manufacturer's part number 39733.