HIGH ACCURACY WITHOUT LOOSENING: The flange adopts a seven hole structure, which can firmly lock your milling machine during use, not easy to loosen, and has higher operation accuracy Er32 Collet Block Set Universal ER32 Collet Chuck,100mm Diameter,7 7 Hole Flange Chuck Collet Chuck ER50 100mm Diameter 7 Holes Carbon Steel For Lathe CNC Milling Carbon Steel Milling Chuck Machifit ER50 100mm Collet Chuck Compact Lathe Tight Tolerance CNC Col... EASY SWITCHING: Threaded chuck allows for quick and easy installation and removal, saving your time when switching between applications Collets 101 is a comprehensive guide covering 5 popular collet series: ER, TG, DA, AF, and RDO; along with care instructions, uses, terminology, dimensions, TIR OXIDATION RESISTANT CARBON STEEL: Made of excellent carbon steel material with black surface treatment, come with strong oxidation obstruction, high hardness and long service life