What a cool little piece of tech, too bad it looks very uncomfortable. The best part about this whole mouse are the very open and detailed schematics included with it. My Unitra Hit record player also has such a detailed schematic and it allowed me to troubleshoot it after I bought it and make it work. I love that a practice like that was standard during socialism and hate that capitalism purposefully obscures how technology works but also how it makes terrible build quality normal. That mouse despite shite ergonomics looked like a tank.
As some comments referred, the Soviets over-engineered things, to make sure they would last forever. Which is the opposite of planned obsolescence. Also, in the 80's ergonomics were non-existent so don't expect much in that regard.