The Felco 902 sharpening stone is made from pure amaril and can be used to sharpen the knives of your pruning shears without having to take them apart. This sharpening stone is easy to use, won't lose its shape and is sustainable. The blue side has medium-sized grains and the white side has fine grains. First you need to sharpen the blades of your pruning shears with the blue side under a 23 degree angle. Afterwards you move the white side over the blades under a 5 degree angle. You can maintain the sharpening stone by keeping it clean with a brush and some detergent.