It''s fabricated by special color glass material. Color Glass Filters are designed by their manufacturers to transmit and / or absorb different wavelengths of light. Tian Cheng optics can supply a full range of filter. They are short pass, long pass, band pass, ultraviolet, infrared, heat absorbing, and color temperature conversion filters. We use material by China to Schott, Hoya, and other manufacturers to process them. Metallic films, colored glasses and thin dielectric films filter are all available per your requirements.