Professional Bonsai Tool Large 11.5" Carbon Steel Knob Cutter/Round Edge Cutter(CSQ280) The spherical knob cutter are designed for removing trunk knobs and roots. The head spherically shaped like a ball. These cutters produce a hollow circular cut that heals quickly with minimal scarring. Compared to standard concave cutters the cutting edges of the knob cutter are rounded. The results are spherical cuts which are round and hollow and heal with the most aesthetic and least visible scarring. 11.5 X 2 X 1 inches