NEMA straight-blade connectors attach to the ends of cables and have socket openings that mate with plugs and inlets 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 receptacles deliver connections in residential and business applications. Industrial connectors have rugged constructions suitable for harsh settings where impacts, corrosion, and hot/cold temperatures are concerns. Hospital-grade connectors are suited for use in healthcare environments and patient-bed locations. Watertight connectors seal out water and debris to provide safe connections in wet and corrosive environments.