The XC-2 bi-directional DTMF to ASCII Transceiver Board converts DTMF decoded from an audio source to ASCII, which is transmitted via the RS-232 serial data port. It also converts ASCII received from the RS-232 port to DTMF, which is then transmitted on the audio line. The XC-2/B is the fully assembled and tested electronics board only version. The XC-2/E is an XC-2/B mounted in a rugged and attractive, black metal enclosure. The XC-2/C (complete) bundles an XC-2/E with the appropriate cable and power supply. Size: 3.50" x 2.50"