CMT 303.000.02 left-hand threaded adaptor M-10/30 has a 19.5 millimeter cutting diameter and a 10 millimeter drill shank cutting diameter. Left-hand rotation. For use on the Alberti, Balestrini, Bilek, Busellato, Schleicher and Vitap. Features high precision and total reliability. Perfectly centered, defect-free rotation, super-strength steel. Precision relief on all surfaces, quick drill change and adaptable to many different spindle nose designs.