Commercial Grade - Thermoplastic Rubber Connectors. Solid brass plug blades are firmly embedded in body. Terminal screw clamps are designed to contain wire and prevent binding. Terminal screws backed out – ready for wiring. Terminals in individual chambers to positively insulate conductors. Combination slot/Phillips head mounting and terminal screws ease installation with power screwdrivers. Commercial Grade - Thermoplastic Rubber Plugs Solid brass plug blades are firmly embedded in body. Terminal screw clamps are designed to contain wire and prevent binding. Terminal screws backed out – ready for wiring. Terminals in individual chambers to positively insulate conductors. Combination slot/Phillips head mounting and terminal screws ease installation with power screwdrivers.