The HSS cutting blade oscillates and therefore is the solution, where a normal, rotating saw blade cannot be used. The cutting line is always visible, and the segmented shape allows for sawing right up to perpendicular surfaces, i.e. cutting right into corners, without over-cutting (see picture below). Used for cutting wood (model building and house decor), fiberglass, carbon fiber, drywall, aluminum profiles, etc. Diameter of the blade is 2 1/2", bore 13/32''. Includes an attachment washer.