Use this ring and collar combo to make a weathertight seal when using an adapter to connect your shore power cord to a dockside power pedestal with a different power configuration than your boat's.
The sealling collar forms a "bridge" between the adapter's connector and the power cord's plug.

Simply slip the threaded ring onto the male plug end of your cordset (which would normally plug into the power dockside shore power receptacle).
Then thread on the double threaded sealing collar. Now mate the cordset plug with the female connector on your adapter, and thread the sealing ring on the adapter onto the other side of the sealing collar.
When all threads are sufficiently tightened, the connection between the power cord and adapter is weatherproof.

Provides maximum moisture protection between a 20 or 30 Amp 125V cordset and dockside adapter
Use with Marinco 20A and 30A threaded systems