The AIWA CSD-TD31 is a portable cassette player that was released by the Japanese electronics company AIWA in the mid-1980s. It is a part of AIWA's popular CC (Compact Cassette) series and features dubbing, auto reverse, bass and treble control, and an external antenna jack. The CSD-TD31 has a sleek and stylish design with a fold-down carrying handle, making it easy to carry around. It was commonly used for listening to music, recording shows or lectures, and playing pre-recorded tapes. While cassette players are no longer as popular as they once were, the AIWA CSD-TD31 remains a collector's item among vintage audio enthusiasts.