Never before has it been such a pleasure to sharpen your knife! Not only are the new Flipstones fun to handle but these diamond and ceramic whetstones will create a sharp edge on any knife. The diamond stone is coated with Titanium Alumina Nitride whilst the ceramic is made of synthetic Sapphires. Both materials are extremely hard and measure 10 and 8 on the Mohs scales of hardness respectively. They will also retain a smooth, flat surface making the sharpening process easier, even with the hardest specialty powder steels. Both stones are sandwiched together using 3M tape and cannot come apart. They are used dry, although a little soap and water can be used to clean the surface. If they feel slightly rough at first they will gradually smooth down and actually improve with age. Instructions: Hold the flipstone in your left hand. Push the catch on the upper section of the handle forward and press the exposed round button. A steel spring will automatically fold out of the whetstone and lock into position. To retract, press the round button and collapse the stone by hand. Fold back the catch to prevent accidental unfolding.