Eisco Round Double Concave Optical Glass Lens - 2" (50mm) Diameter - 50mm Focal Length - 13mm Thick Approx. - Labs

EISCO Double Concave Lens, 50mm Focal Length, 2" (50mm) Diameter - Spherical, Optically Worked Glass Lens - Ground Edges, Polished - Great for Physics Classrooms

EISCO Double Convex Lens, 1000mm Focal Length, 3" (75mm) Diameter - Spherical, Optically Worked Glass Lens - Ground Edges, Polished - Great for Physics Classrooms

Amlong Crystal Premium Optical Glass Double Convex and Concave Lens Set, 50mm Diameter, 3 Double Convex (20, 30, 50cm FL) and 3 Double Concave (20, 30, 50cm FL), 6 Piece Set