3” x 21” sanding belts made from a Zirconia blend grain in 24 grit Zirconia abrasive grain features PolyCotton "X" weight backing Sanding belts feature a butt joint for a consistent and smooth finish and extended belt life This Zirconia and Aluminum Oxide blend provide faster cutting and longer life Excellent for all purpose sanding - and specifically for use on aluminum, steel, composite and hardwood These 3 Inch X 21 Inch cloth sanding belts are made with premium German engineered Starcke material. All our sanding belts are made custom to order in grits 24 - 120. This Zirconia abrasive grain features Poly Cotton "X" weight backing. These sanding belts feature a butt joint for a consistent and smooth finish and extended belt life. A full resin bond allows for long lasting performance. This high performance abrasive is excellent for carbon steel and hardwood. Zirconia is also great for tough grinding applications like stainless steel and titanium. Belts are available in packs of 4, 8 and 12.