Supplied in a metal storage box, complete with collets Metric chucks are supplied with 6, 10, 12, 16mm collets, enabling them to hold any cutter from 1.5 to 20mm diameters Imperial chucks have 1/4, 3/8, 1/2, 5/8 inch collets, making them suitable to hold any cutter from 1/16 to 25/32 inch diameters Self-centring & automatic locking, this ensures the cutter is unable to slip, pull out, or push back The heavier the cut applied to the material, the tighter the grip produced on the milling cutter.