Sandpaper is a coated abrasive sheet used for smoothing down rough surfaces or removing a layer of material such as paint. Shark Blades Sanding Sheets/Papers come in a variety of sizes and grits. The grit number refers to the size of the particles embedded in the sandpaper. The lower the number, the larger the particles which will remove more material leaving a rougher finish. The larger the number, the smaller the particles which will remove les material but leave a finer, cleaner finish.