The 3M 346U 40 Grit Production Sandpaper Sheet is built for the toughest sanding jobs. Featuring extra coarse aluminum oxide abrasive on a strong 9″ x 11″ D-weight paper backing, this sheet is ideal for rapid material removal, heavy paint and rust stripping, and surface leveling on wood, metal, and fiberglass. Its open-coat construction helps reduce loading for smoother sanding and improved efficiency in high-debris applications. Durable and long-lasting, the 346U production sheet is designed to perform under pressure in demanding industrial and workshop environments. Whether you’re preparing surfaces for refinishing or aggressively shaping materials, this extra coarse abrasive delivers fast, consistent results and dependable strength for both hand and machine sanding.