NEMA locking-blade plugs and receptacles are made to standards designated by the US National Electrical Manufacturers Association. They secure when twisted to prevent unintended disconnections. NEMA devices are rated for different current ratings and use various pin/socket configurations to prevent mismatched connections. Plugs attach to cables and have terminals that insert into connectors and receptacles. Connectors attach to cables and have socket openings that connect with plugs and inlets. Receptacles mount on surfaces and have socket openings that accept plugs. Inlets secure to surfaces and equipment and have pin terminals to secure connectors.