The Spectrum 4.50" Full Aperture Film Solar Filter- 105mm to 111mm is a premium quality polymer film filter meant for safe and comfortable solar astronomy, both imaging and visual. These economically designed filters provide natural, high clarity solar views for your perusal and use when used with an appropriately sized telescopes, and are made with high quality polymer film combined with high reflectivity coatings. The Spectrum 4.50" Full Aperture Film Solar Filter is sized with an O.D. Measurement of 105mm to 111mm, leaving it the perfect size for use with a wide array of telescopes with matching OD's.