Terminal Blocks are modular, insulated, screw-type electrical connectors that are used to secure and/or terminate two or more wires together. Useful for connecting wiring to a ground or for connecting electrical switches and outlets to the mains. Molded Bakelite and stamped brass construction. Designed for use with tinned copper marine wire which shares the same expansion rate to prevent loosening wires and reducing electrolytic corrosion caused by pairing two disparate metals. Installs with four #6 RH fasteners (not included). 20A. Terminals 4 A 1-1/8" B 7/8" C 2-1/2" D 5/16" E 1/2"