Household knives have been used for a long time and it is inevitable that they will rust and become impractical, so I bought this whetstone and was pleasantly surprised to receive it because it is a whetstone. It can be sanded finer or coarser. The function is very powerful. I use knives for polishing at home and the polishing time will not be too long. This takes about 5 minutes. Knives become sharp, enough for everyday use, very satisfied