Here you get a set consisting of 5 different grain sizes.

120-220-400-600-1000 grit

The manufacturer is the Grinderman company in Russia.

The stones are at least equivalent to the American boride stones.

Just a third cheaper.

I got 10 sets cheaply and pass them on at a top price.

For all knives that are not necessarily ground with CBN stones (always depends on the steel) these stones are a great alternative.