Got the first 3 knifes free and I still have an extra third knife to arrive sometime this year. I bought the last three in December.
The stone is very low in the grit scale though something like 200/400 but i am not bothered as I already have a Naniwa Combi Stone 120/1000 and Naniwa Super Stone 2000/5000. So that should keep them all in pristine condition for a long time.