A half stop neutral density. (Trans.= 70%).Rosco's premier range of filters, Roscolux, is manufactured in a unique technology to insure the longest possible life under hot theatrical lights. Three discrete layers are combined in a tri-extrusion process. By sealing the colored layer between two microscopically thin layers of clear film, dye migration is minimized and effective life is extended. Roscolux (sold under the trade name "Supergel" overseas) is currently the most widely used filter range in the world.Roscolux is comprised of two types of plastic. More than 65% of the line is made from co-extruded polycarbonate plastic. The remainder of the line is deep dyed polyester.Ordinary color filter is manufactured by surface coating clear polyester plastic film. In essence, the color is painted onto the surface. This means that heat and physical abrasion can easily remove the dye, resulting in quick fading and scratching.Available in sheets of 20in. x 24in. (50cm x 61cm) or rolls of 24in. x 25ft. (61cm x 7.62m). If you require rolls of larger dimensions the Cinelux line of filters is available in rolls of 48in. x 25ft. (122cm x 7.62m).