Orion 07761 Deluxe Safety Film Solar Filter 10.56 Inch Inside Diameter (Silver) Explore the Sun safely through a telescope with this high-quality solar filter featuring Baader film in a sturdy aluminum cell Fits 9.25 Inch SCT and Celestron CPC 925 telescopes Each filter is mounted in a foam-lined, clear-anodized aluminum cell featuring three equidistant securing thumbscrews for secure telescope attachment This filter features an inside diameter of 10.56 inches - it is designed to fit optical tubes with an outer diameter of 10.31 inches to 10.56 inches" with included shim materials and securing thumbscrews Note: All Orion solar filters are designed for use with an adequate friction fit attachment. Thumbscrews should only be used to keep filter securely in place once a friction fit has been achieved