Technical details, specifications
Leak-proof headphones of the new generation walkman
The WM-190 is very similar to the WM-EX49, the only differences are minor styling changes and that it can run from a rechargeable battery only, there is no internal provision for an "AA" cell. This makes the casework slightly thinner and neater, an external holder for an "AA" cell can be attached to the bottom of the unit if required.
Once the Walkman became a necessity, the problem was that headphones would leak in confined Spaces such as trams. The wm-190, though, is basically airtight to reduce leakage.