3Mâ„¢ Trizactâ„¢ Rolocâ„¢ Cloth Disc 237AA uses proprietary microreplication technology where micron-graded aluminum oxide particles are formed into tiny pyramids of abrasive mineral and then coated on an X weight cloth backing. As these pyramids wear, fresh, sharp mineral is continually exposed to produce a consistent cut and a predictable, fine finish.