Camco® 39471 Revolution Swivel Bayonet Elbow & 4 - in - 1 Adapter.
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!
Connects to lug fitting on sewer hose. Features built-in gasket for an odor-tight connection. Translucent Elbow detaches from 4-in-1 Adapter to fit into 4" RV bumper. Manufacturer's part number 39471.