Essentially, a Russian take on a single-row melodeon originating from the region of Saratov.
With some extra bells & whistles. Literally.
Traditionally, they had cassotto in the treble side. In fact that's not the only Russian traditional harmonika that had cassotto, they might have invented it well before Germans or Italians started incorporating it in their instruments.
You can use google translate and read this little article.
Материал о возникновении и развитии саратовской гармоники
poigarmonika.ru
Bisonoric squezeboxes (1-, 2-, 3-, 4-rows, usually with extended bass compared to European counterparts) were standard until about 1950s, when the Party decided to suddenly stop almost all production of bisonoric instruments and any related literature, and told soviet harmonika players that they all need to switch to the "hromka" unisonoric diatonic model. A huge amount of information about traditional bisonoric instruments has been lost, and today you'd really struggle to find any sheet music for them. Most of the tradition has been lost, but afaik there's a little bit of effort these days to preserve whatever little has been left. Just how HIP and authentic the result, is open to discussion.
I expect that you'll be able to play the usual single-row box repertoire from all over the world. The problem with any accordion mass-produced in a soviet factory is that you usually can't treat it as an accordion - you have to treat it as a parts kit that can be rebuilt into an accordion that actually works. In most cases, you get horrible reeds, horrible mechs, horrible woodwork, close to zero set-up and non-existent QC.
Sometimes there are pleasant exceptions to this rule, so I hope you have a good one.
f history to this instrument.
