Kutzall burrs are the perfect companions for your rotary carving tools, designed to work easily and efficiently where other conventional tools fail. Proudly crafted in the USA, they perform with remarkable wear-life and provide a truly unique combination of superior material removal and surface quality. With effortless operation (with or against the grain) and resistance to loading, you'll use them project after project. Their outstanding performance on a wide variety of materials will keep them locked in your favorite grinder. Wood, plastic, drywall, rubber, fiberglass, and soft stone, they will be your go-to workhorse for any task. NOTE: Should only be used on non-metallic materials. Sphere - The Sphere Burr is the perfect option for when you need to hollow out a concave surface, or produce a radius. Need to produce an undercut or overhung edges? This burr is the easy choice. Original Coating – Creates a smooth cutting action and is easy to control; works exceptionally well on harder woods. Diameter and head length dimensions on Kutzall burrs are base dimensions. The coatings add approximately .060" - .102" Compatible with popular grinders with 1/8” collets or adjustable chucks including: Dremel, Foredom, Dewalt, Milwaukee and more. Recommended operating speed range is 10,000 - 25,000 RPM. They will remove material at lower speeds (hand drills, drill presses) but both material-removal rate and control improve as speed increases. Cleaning: They can be easily cleaned using a torch and/or a quick few passes with a soft wire brush, the heat will not harm the teeth!