ST18 Cable Mount Plugs and Sockets Three pole male and female connectors available as standard (single screw terminal), standard with cable strain relief (single cable diameter 6.5 - 8.3mm), standard with dual strain relief (two round cables 4.5 - 10mm or one flat cable) or double screw with dual strain relief (houses two separate screw terminals so that two cables may be terminated on one pole - ideal for lightchains, jumper connections or additional branches). Strain relief types include top cover.