3M 9" x 11" PRODUCTION PAPER SHEETS - 210N, 336I, 346I AND 346U is for dry sanding only by machine or hand. For use on Fiberglass, wood or metal. Open coat with rough aluminum oxide mineral. Sheet is 9" x 11". The 210N Series is on "A" weight backing paper, 336I is on "C" weight backing paper, and the 346I and 346U Series is on "D" weight backing paper. Product is sleeve of 50 sheets. 10 sleeves per case.