ADSL Microfilter Adapter Type An ADSL microfilter is used to separate the phone line connection from the internet connection reducing interference and dropouts or even connection problems. For each te more→lephone or device that uses a phone line a microfilter must be plugged inSpecification: ADSL Microfilter 1x BT Plug - 1x BT Socket / 1x ADSL Socket T Shaped Adaptor Passive