Knife sharpening angle blocks from 10 to 30 degrees in 5 degree increments. Up to 10 degrees for razors blades. 15 to 20 degrees for kitchen knives. 15 to 25 degrees for pocket knives. 30 degrees and above for hatchets axes etc. Groove cut into the blocks to use rubber bands to hold to the sharpening stone. Break off the angle you need from the strip.