As used on Sky TV installations to provide the telephone line to the digibox for interactive services. Adaptor with 431A (4 way) BT plug which provides two BT (431A 4 way) sockets & the ability to hardwire an extension off the numbered IDC terminals. No tools required as the adaptor contains an integral IDC snap down block. They have been designed to accept CW1308 telephone cable (round, solid conductor, 2 pair, 4-core). Can be used for other telephone applications.