NEMA straight-blade plugs attach to the ends of cables and have terminals that insert into receptacles and connectors to distribute power. They're made to standards designated by the US National Electrical Manufacturers Association, have different current ratings, and use various socket configurations to prevent mismatched connections. Commercial plugs deliver connections in residential and business applications. 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.