Prima I Key Type Drill Chuck Impact-resistant key-type drill chuck. Conical/threaded mount with DIN ISO 10887 (toothing in acc. with DIN 6349). Prima I for use on stationary drills and machine tools Features For clockwise and counterclockwise rotation. Thread or taper mount for maximum drive force and precision Increased clamping force due to proven transmission principle from sprocket and drill chuck key Universally applicable for stationary box column drills, machine tools High concentricity of up to 0.15 mm