Orion 07760 Deluxe Safety Film Solar Filter 9.25 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 Each filter is mounted in a foam-lined, clear-anodized aluminum cell featuring three equidistant securing thumbscrews for secure telescope attachment This filter has an inside diameter of 9.25 Inches - it is designed to fit optical tubes with an outer diameter of 9.0 Inches to 9.25 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