Ceramic aluminum oxide, a self-sharpening grit that is harder, tougher, and lasts longer than aluminum oxide
Cloth backing, for a stiffer, tougher, and thicker backing than paper or film
Flap wheels conform better to the workpiece than a disc, and are commonly used for grinding and finishing on irregularly shaped workpieces
1/4"-20 threaded spindle for use on threaded toolholding systems
Super finish flap wheel conforms to the area being finished, helping to give a very smooth finish