Decepticon Communicator Soundwave transformed from robot to replica cassette deck and back. His cassettes were also Transformers, and could fit inside of his chest one at a time. They could be ejected like a cassette as well.
Soundwave came with Buzzsaw, a Transformer that turned from condor robot to cassette. He also came with several small accessories, instructions for transformation, and biocard on back of package.
Collector's Note: Variants of Soundwave exist.