The Precision Brand® Steel Arbor Shim Assortments are used for fast, accurate spacing of milling cutters, gang cutters, saws, slitting blades, and grinding tools. It is Made of high quality, low carbon, cold rolled, full hard, steel shim. Arbor shims have no keyways. It Saves time over re-machining. It has precision thicknesses for more accurate results. Packaged in airtight poly bag. Assorment contains one each of 19 different thicknesses.