I have a pair of battery-powered speakers from DAK ca. 1984 that still work. Comes in a carrying case with a cubby for the Walkman it's designed to work with.

I have a pair of battery-powered speakers from DAK ca. 1984 that still work. Comes in a carrying case with a cubby for the Walkman it's designed to work with. Edit: Turns out it's on p.30 of this catalog.