Whiteside RFTD2100 Spiral Flush Trim Down Cut1 4"SH, 1 4"CD, 1"CL Providing state of the art results in flush trimming. The bit uses a double ball bearing pilot to run against your project template while the down cut flutes expel chips down and away from the router, leaving a smooth top surface. Materials: Natural woods, composites, hard plastics, thin aluminum Recommended RPM: 18,000 20,000 (max 24,000)