The Jacobs Rubber Flex Tap Collet features parallel jaw insert surfaces that exert uniform, accurate gripping force up to three times greater than can be achieved with split-steel collets. Each Jacobs collet accepts and precisely centers a wide range of both decimal or metric diameters (within the collet capacity range) to speed setups and increase machining productivity. Jacobs collets are made of a durable one-piece construction, synthetic rubber that retains flexibility and resists deterioration from heat, coolants and cutting compounds, and steel jaw inserts precision ground after molding process to ensure maximum gripping accuracy. Jacobs collets are hardened for greater wear resistance than split steel collets, and each collet bore is held concentric to the o.d. tapers, front and back, to minimize T.I.R.These Jacobs Collets also automatically seal tool O.D. to prevent coolant flow through thus increasing tool wear, and it seals collets and machine spindles to protect from abrasive particles and swarf.