418036 Silicon Carbide 12″ x 18″ Floor Sanding Sheets, 36 Grit (20 pack). 20 – Precut sheets for any 12″ x 18″ buffer – square buff, Clarke, deva, silver line. For hardwood or concrete. Silicon Carbide grain gives a consistent performance at a competitive price. Extra Heavy weight paper backing provides extra durability, high tear resistance. Backside of sheet has enough grain on it to adhere to a sanding pad. Available in grits 20 through 100 for all your sanding needs.