Both Professional/Commercial quality sandscreen discs. Professional quality screen discs are longer lasting screens used primarily for resurfacing hardwood floors of all types. The discs sand down old finish so that new finish can be applied. This is known as the "scour method" of refinishing a floor and is most often used on gym floors. Manufactured with waterproof resins and silicon carbide abrasive, assuring you of the finest quality Professional discs you can buy. Commercial quality superscreen discs are also used primarily on hardwood floors and are a great value. These Commercial screen discs come in grits ranging from extremely coarse to super fine.