Instruction: JDK diamond Vacuum brazed diamond profile router bit use Vacuum Brazed Technology, hand profilers give you aggressive grinding action and longevity, without losing the shape of the profiler, unlike the Sintered profilers on the market. The optimal speed to use the grinder is 3,500-4,000RPM. It can be used wet or dry, fit on any variable speed polisher with 5/8-11 thread spindle is available for most of grinder and polisher. materials as Processing: Granite, Engineered Stone, Porcelain, Marble and Limestone. Can be used on concrete also, but life will be short due to the abrasive nature of concrete. About JDK: JDK has been engaged in manufacturing and exporting worldwide quality diamond tools since 1995. JDK products include a series of Cutting, Grinding, Profiling and Milling tools for processing hard and fragile materials, such as Natural Stone, Ceramic Tile, Concrete etc.