This came with batteries but it did not work very well at all. The knife goes in under the grey parts. It took a lot of drags for the knife to get an edge. I went back to using the one above, but I had an awful feeling it would all go ever so wrong one day. I am not know to be a person with a steady hand. R encouraged me to get a replacement that actually worked.
We found this one made by Scanpan for a few more dollars than the battery one above. It is beautifully designed and works very well. If your knife is very blunt, you start with with the slot with the coarsest stone and follow up with the progressively finer stones, that is left to right. I do like it when things just work.