Hurricane 7" CBN Grinding Wheel, 180 Grit, 1.0" Wide, 5/8" Bore, for Sharpening High Speed Steel Tools CBN (Cubic Boron Nitride) Grinding Wheels are State of the Art Technology for Grinding High Speed Steel Tools These wheels are designed for use with bench type grinders. 1800 RPM (Preferred) or 3600 RPM Ideal for Sharpening Woodturning Tools (High Speed Steel Only) Provides a superior edge compared to stone wheels Balanced. Does not require "truing" of the wheel