WM-10RV

The WM-10RV was the final major version of Sony's stretchable WM-10 family and the model that brought the concept closest to feature completeness. Released in 1984, it added auto-reverse and Dolby B noise reduction to the collapsible metal chassis while keeping the single-AA battery system, step-up converter, Disc Drive-based transport, and expandable form that made the line recognizable. The body became slightly thicker and heavier to accommodate the more complex mechanism, but the machine still preserved the essential cassette-sized compact logic of the original concept.

It closes the stretchable branch in exactly the right way: not by replacing the idea, but by proving how far it could be pushed before the compromises became too large. The WM-10RV was the final and most resolved expression of one of Sony's most distinctive early Walkman concepts.