Orion 07733 4.10-Inch ID Full Aperture Glass Telescope Solar Filter (Silver) A must-have filter for safe observation of the sun through a telescope without damaging your eyes - optical glass filter fits snugly over your telescope's aperture to block 99.9 percent of incoming sunlight Fits Orion Observer 70mm, ShortTube 80mm, StarSeeker 80mm, and AstroView 90mm refractors; Apex and StarMax 90mm Mak-Cass telescopes; and other models Each Orion telescope solar filter is mounted in a foam-lined aluminum cell featuring three equidistant securing thumbscrews, 4x 1/16 inch thick adhesive foam tabs, and 4x 1/8 inch thick adhesive foam tabs for customized friction fit to your telescope Filter inside diameter is 4.10 inch - fits optical tubes with an outer diameter of 3.85 inch to 4.10 inch 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