There are two spring loaded Aluminium Oxide grinding wheels (coarse and fine), which apply a controlled pressure to the blade of the knife. Please note that this machine is a sealed unit and there are no replacement parts, however, under normal profile use, the sharpening wheels are guaranteed for life.
The grooves in each section hold the knife at a 15º angle giving you a perfect cutting edge, which is impossible when using a steel.
The left groove in each section sharpens the right hand side of the knife and the right groove, the left side. The knives are sharpened in the coarse section (marked 1) and polished to a razor finish in the fine section (marked 2).