Koyo Professional Grade Spherical Knob Cutter 7"
Bonsai Knob Cutters are designed for removing ugly knobs from trunks and branches without leaving an unsightly callous when the cut heals. They can also be used to hollow out the cut after a concave branch cutter is used. Though not usually a beginner's tool, most bonsai artists wouldn't be without one
Made in Japan by Koyo, a quality tool maker