WM-45

The WM-45 is the North American version of the sports-oriented WM-35 and one of Sony's clearer early attempts to push the Walkman into more active, outdoor use. It uses a tougher body built to better tolerate movement and everyday physical handling, while keeping the cassette mechanism very simple with two-AA power, manual tape selection, and playback-only operation. There is no Dolby or advanced circuitry to complicate the player.

This model sits early in the Sports Walkman story, before the concept fully hardened into its later waterproof and heavily stylized identity. It is still a normal cassette player that had simply been made tougher, not yet a fully separate branch.