These 1/2 Inch X 18 Inch cloth sanding belts are made with premium German engineered Starcke material. This Aluminum Oxide abrasive grain features Cotton "X" weight backing and features a butt joint for a consistent and smooth finish and extended belt life. This premium high performance abrasive is used on air file belt sanders and is excellent for all purpose sanding - and specifically for use on Aluminum, Steel, Composite, Hardwood, and Softwood.