Contains 1 of each thickness: 0.001?, 0.0015?, 0.002?, 0.003?, 0.004?, 0.005?, 0.006?, 0.007?, 0.008?, 0.010?, 0.012?, 0.015?, 0.020?, 0.025?, 0.031?, 0.047?, 0.062?, 0.093?, and 0.125?. Made of high quality, low carbon, cold rolled, full hard, steel shim. Arbor spacers are used for keyed applications. Keyway size: 1/2? x 3/16?. Packaged in airtight poly bag. Precision Brand Arbor Spacers are used for fast, accurate spacing of milling cutters, gang cutters, saws, slitting blades, and grinding tools.