Bob Kramer is widely recognized for his extremely sharp high performing carbon steel knives. To keep these knives maintained and sharp, Bob Kramer by Zwilling has introduced an entire collection of water stones. Each water stone is made from a synthetic ceramic. Grit #400 will change the angle of the edge and also repair the knife blade from nicks & chips, #1000 grit is used for fine sharpening, #5000 grit is for extra fine finishing, polishing and will place a very sharp edge onto the knife blade. These stones are safe to use on all knives except ceramic. The bamboo whetstone sink bridge creates an ideal work station and will adjust to fit various sink sizes. A cleaning stone is also included in this kit to polish and clean your ceramic whetstones along with a Bob Kramer instructional DVD to guide you on how to make and keep your knives razor sharp. 16.25" x 3" wide sink bridge closed.