The MX42 is a four channel stereo mixer. The unit mixes up to four stereo RCA signals such as CD or cassette players with VCR units, even computer sound cards or MP3 players. All signals are mixed via stereo 100K ohm potentiometers to stereo RCA output connectors. The unit is passive, requiring no power. Features: Dimensions - 3 x 2 x 1.42 (W x H x D) Weight - 1 lb.