TAPER MOUNTED MEDIUM DUTY MODEL Fluted sleeve standard except for Model 0 and 1A, which are smooth and ground. The Jacobs Plain Bearing Chuck is the world's most widely used for medium or heavy-duty portable, bench or floor mounted power tools. This industrial quality chuck, with fully hardened and ground working components, offers exceptionally high accuracy, gripping power, and durability. Both heavy and medium-duty models are available in a wide range of capacities for use on threaded and taper mounted spindles. FEATURES: Heavy and medium Duty models for threaded or taper mounting. Jaws center-ground for absolute straightness and alignment. Jaws specially treated to ensure extended thread life and high gripping surface hardness. One-piece sleeve eliminates crack between driving teeth often found in other designs. Through-hardened sleeve teeth plus hardened nose and keyholes provide outstanding wear resistance. Each chuck 100% inspected for performance and precision.