WM-2051

The WM-2051 is a basic playback Walkman that added two meaningful conveniences to a stripped-down package: auto-reverse and metal-tape compatibility. It uses a compact body and a straightforward layout built around uninterrupted cassette playback instead of around audio enhancement or extra branches like radio. This model stayed focused on doing a compact number of things correctly and without fuss.

You can see how features that once felt relatively advanced had by 1990 become normal enough to appear in modest, lower-cost playback machines. Sony was no longer using auto-reverse only to differentiate more expensive products. That makes this a compact but useful sign of maturity in the line.