Eisco Labs Double Concave Glass Lens, 75mm Diameter, 30cm Focal Length Go to amazon.com Related posts How to find the best convex concave lens for 2022? FeatureDiameter = 75mmFocal Length = 30cmMade of glassBeveled Grounded EdgesDouble Concave DescriptionEisco Double Concave Glass Lens, 75mm Diameter, 30cm Focal Length