The master socket contain a surge arrestor and an R/C Circuit filter these are used by your service provider to get a fixed value resistance when they run line checks. Standard BT Type socket with Screw Type terminals.
Made from High quality ultra slim, premium grade material Complete with Integral gasket for moisture protection Minimum Mounting depth: 25mm Dimensions: 87.5mm x 87.5mm Supplied in Retail blister with full Fitting instructions Compliant to BS 5733 15 Year Manufacturer Guarantee.