The 1st stage is electric and has the most abrasive disk to raise a burr and create the 1st bevel edge. The 2nd stage is manual and has a small butcher's steel to steel the edge and create micro sharp serrations in it. The 3rd Stage is electric and has a flexible stropping disk to polish/straighten the blade and create the 2nd bevel. The 3rd stage can also be used to sharpen serrated knives.
The 1st and only stage is electric and quickly sharpens the edge to an 11° angle.
The brown, medium grit stones are used in the 1st and 2nd stages, and the white, fine grit stones are used in the 3rd and 4th stages. During the 1st and 3rd stages, the blade is pulled over the triangular edges of the stones, and, during the 2nd and 4th stages, the blade is pulled over the flat edge of the stones. The corners of the white stones can be used to sharpen serrated edges. For extremely dull knives, Spyderco diamond embedded abrasive stones can be purchased separately.