Jacobs 9747 J420 Rubber-Flex Tap Chuck Collet Capacity 0.176-Inch to 0.320- Inch (4.5 to 8.1 Millimeter),Jacobs Chuck,9747" /> Parallel jaw insert surfaces exert uniform, accurate gripping force; Each collet accepts and precisely centers a wide range of both decimal or metric diameters to speed setups and increase machining productivity Durable one-piece construction; Synthetic rubber retains flexibility and resists deterioration from heat, coolants and cutting compounds Steel jaw inserts precision ground to assure maximum gripping accuracy Each collet bore is held concentric to the O.D. tapers, both front and back, to minimize T.I.R.; Automatically seals tool O.D. to permit coolant flow through tool reducing wear. Seals collets and machine spindles to protect from abrasive particles and swarf