The Spyderco 303MF Doublestuff combines the 303F (fine grit) and the 303M (medium grit) in one tool, offering multiple sharpening alternatives. For optimal performance, it's recommended to use the tool dry, and avoid applying oil, water or lubricants. Cleaning is easy and can be done using a plastic scouring pad coupled with a powdered abrasive cleanser. For your convenience, this pocket stone comes complete with a durable leather carrying case.