This bit has bit has been up graded to the RBN-831-1150 for faster, better cut outs!  

Then New RBN-831-1150 only removes 1/2" of material greatly reducing the drag of the cut, the amount of dust being produced, and speeds up the process immensely.  The Delrin Bearing sleeves a 1/2" steel bearing.  Because the effort needed to remove the sink cutout due to the single flute cut, the bearing rolls on the side of the sink effortlessly reducing the pressure and friction that sometimes causes the bearing to fall apart.  If (which should never happen with proper bit maintenance) the sleeve were to fall of, the 1/2" bearing will not allow the cutter to cut into the sink!  This is a great improvement over past cutout bits and you are sure to notice the difference!  This bit leaves a 1/8" overhang.