. 2" x 1" Mounted Flap Wheel - 1/4" Shank - Ceramic Oxide - 120 Grit Active grinding additives in the coating substantially improve the stock removal rate, prevent loading and result in cooler grinding. The abrasive grain is embedded in the sturdy, flexible cloth backing material by means of a resinoid bond. On mounted flap wheels, coated abrasive flaps are arranged radially around the wheel axis in a fan-type structure.