Morris Products 90568 One Conductor Connector, Extruded Style, Copper, 4/0 - 14 Wire Range Copper Mechanical Connector Extruded Style One Conductor - 1 Conductor extruded Copper MechanicalConnector is best for copper wire connections Solid One-piece 1 Conductor Copper Connector made from Extruded Copper for superior mechanical strength and excellent electrical performance 1/4" Hex Head Screw Suitable for Use with Copper Wire only Copper Mechanical Connector is rated 600V