Naniwa Super Stone coarse 400 Grit Japanese Whetstone Sharpening Stone, 21cm x 7cm surface, 2cm thick.
The Naniwa Super Stones are excellent whetstones, very reliable, forgiving, and not fragile. A GREAT choice for the beginner or casual home user who just wants good long-lasting stones that work great on a variety of knives. I use these SuperStone series at home and they're great. They're also easy to use: just splash-and-go, no need for soaking and in fact they should NOT be soaked.
This coarse stone is perfect for grinding a new edge on your knife, and for working out nicks or cracks or other imperfections in old used/abused/damaged knives. Use this grade only when you regular maintenance and finishing isn't doing the trick anymore. It's quite coarse and so will cut (remove metal) quite aggressively and quickly.
Note: these are now branded "Super Stones" again... in 2015 Naniwa re-branded them "Sharpening Stones" for the North American market, but I think they finally realized that didn't make sense so they're gone back to the better-known "Super Stone" name.
These are excellent stones! High quality, long-lasting, great value, not fragile.
Warranty: One-year warranty against manufacturing defects.