Stack cutting annular cutters available for drilling multiple layers without stopping to remove center plugs. Stack cut tooth geometry cutters will smoothly penetrate multiple layers where non-modified cutters cannot. At the core of the RotoBrute system is the broadest range of HSS annular cutters available which feature our exclusive Plus20 surface treatment for provides cleaner cuts, positive slug ejection, and long tool life. Comparative tests show that RotoBrute Plus20 cutters perform up to three times longer, providing they are used with cutting fluid, proper speeds and feeds and not subjected to user abuse. The unique combination of geometry, metallurgy and special surface treatment produces a truly superior annular cutter resulting in improved performance, tougher cutting edges, less chip welding, better wear resistance and reduced friction, easier cutting action and less stress on machine motor.