NEMA locking-blade plugs attach to the ends of cables and have terminals that insert into receptacles and connectors to distribute power. They secure when twisted to prevent unintended disconnections. These plugs are made to standards designated by the US National Electrical Manufacturers Association (NEMA). They are rated for different current ratings and have various socket configurations to prevent mismatched connections. Industrial plugs have rugged constructions suitable for harsh settings where impacts, corrosion, and hot/cold temperatures are concerns. Hospital-grade plugs are suited for use in healthcare environments and patient-bed locations. Watertight plugs seal out water and debris to provide safe connections in wet and corrosive environments. Hazardous-location plugs supply power in settings where ignitable gas, vapor, liquids, and fibers may exist under normal and abnormal conditions.