Master and Secondary telephone sockets. Master sockets contains surge arrestor and an R/C circuit filter used by service providers to get a fixed value resistance when they run line checks. Standard BT socket with screw type terminals. RJ45 Network outlet is ideal for creating wired networking points around the home, is UTP CAT5e compliant and comes with IDC terminals. Made from high quality ultra slim, premium grade material. Complete with internal gasket. Compliant with all relevant British Safety standards.