Thousand Oaks Solar Filter Type 2+ Full Aperture for Celestron 11" Schmidt-Cassegrain telescopes.
Type 2 Plus: Made with high quality hand select glass coated with our exclusive Solar II Plus. The most durable glass filter on the market. Transmission is 1/1,000th of 1% (Optical Density 5). Great for both visual and photographic use. Solar image is yellow-orange. Guaranteed fifteen years.