4.30" ID Set of Orion Binocular Solar Filters A must-have set of two solar filters filter for safely observing the sun and sunspots without damaging your eyes or your Orion 20x80 Astronomy Binocular optics Optical glass filters fit snugly over each binocular objective lens to block 99.9% of incoming sunlight Glass elements are machine-polished and triple-coated with nickel-chromium stainless steel Each Orion binocular solar filter includes three equidistant thumbscrews, 4x 1/16" thick adhesive foam tabs, and 4x 1/8" thick adhesive foam tabs for customized friction fit to your binoculars 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