ADSL Filtered BT Faceplate Integrates an ADSL microfilter into a standard BT socket. Although supplied with a surface mount back-box for convenience, the faceplate is replacement compatible with existing BT extension sockets. Connections are provided at the rear to enable further ordinary extensions to get a filtered or unfiltered signal. This device is The 85mm version matches the standard electical socket of the type used with plaster/board mount back-boxes.