The Sony WM-F55 is a portable cassette player that was released in the mid-1980s. It features a built-in FM/AM radio tuner and offers a compact design that was popular for personal audio in that era. The device is powered by batteries, making it suitable for on-the-go use. It includes features such as automatic level control and a built-in microphone for voice recording. The device is often remembered for its unique styling and sound quality for cassette playback.