Orion 07754 Deluxe Safety Film Solar Filter 4.3 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 Orion Go Scope II 70mm, Go Scope 80mm, and Celestron NexStar 90 SLT telescopes 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 4.3 inches - it is designed to fit optical tubes with an outer diameter of 4.05 inches to 4.3 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