The SignaLink USB combines the excellent performance of the SL-1+ with a revolutionary built-in low-noise USB sound card. The ground breaking innovation delivers optimum performance while eliminating the need to use your computer's sound card. It has convenient front panel controls and with its simplified installation makes it one of the most user-friendly interfaces on the market. All sound card Digital and voice modes are supported by the SignaLink USB. This includes traditional modes such as RTTY, SSTV and CW, as well as the latest modes such as PSK31, MT-63 and Echo Link. Ease of operation is provided by front panel controls that let you adjust your transmit audio, receive audio and transmit delay. The SignaLink USB will work with all radios (just select appropriate SignaLink model) and it can then be attached to the Mic. jack, Data port or Accessory port. The most common approach is to attach the unit to the back of the radio (Data or Accessory port) and keep the microphone plugged in the front of the transceiver. It measures 3 1/2" x 3 1/2"x 2 1/2". The item has been tested and is in functioning working condition.