This is a replacement for the (internal) receptacle in a 50A 125V dockside shore power pedestal.
Receptacles are susceptible to damage from overheating due to a loose, pitted, or corroded connection, or a damaged power cord.
Heat damage is most often indicated by a brown discoloration at the base of the plug blades or around the sockets in the receptacle.
Damaged shore power components are a potential fire hazard and should be replaced immediately.

Black, glass-filled nylon body and face provide excellent weathering resistance
Corrosion resistant marine grade internal components


Heavy on the technical side...

There are two categories of 50 Amp devices: 50A 125V (50A 3-wire), and 50A 125/250V (50A 4-wire).
The 3-wire devices have a single "hot" leg carrying 50A 125V.
The 4-wire devices have two "hot" legs, each carrying 50A 125V. (50A 250V when combined.)
These two categories are NOT interchangeable.
Never alter the plug of one type of these devices to fit into the receptacle or female connector of the other type.