Plugs and connectors are used to connect equipment to a power supply. Straight-blade plugs and connectors are compatible with straight-blade receptacles and are used in residential, commercial, and industrial applications. Locking plugs and connectors are locked in place with a twisting motion to prevent them from accidentally disconnecting. Midget locking devices are smaller than standard-size locking devices are require less space when installing them. Pin-and-sleeve plugs and connectors keep dirt, grime, moisture, and other elements away from electrical connections. Mechanical interlock devices are receptacles that allow compatible plugs to be attached only when the power is turned off, and they prevent the plug from being removed from the receptacle while the power is on. Single-pole devices include connectors and receptacles that have a high amperage capacity.