With unmounted flap wheels, coated abrasive flaps are arranged radially around the core in a fan-like structure. The flexible flaps perfectly adapt to surface contours. The abrasive grain is embedded in the sturdy, flexible cloth backing material with a resinoid bond. In ISO 5429, unmounted flap wheels are designated as "flap wheels." The ideal flap wheel for use on angle grinders in assembly shop operations. For aggressive grinding with maximum stock removal rate on hard materials which do not conduct heat well. Consistently high performance due to self-sharpening ceramic oxide grain. Active grinding additives in the coating substantially improve the stock removal rate, prevent loading and result in cooler grinding.