EISCO Optical Glass Lens Set - 3 Dbl Convex, 3 Dbl Concave, 38mm Dia - 20, 30, 50cm FL;

Optical Glass Lens Set, 6 Lenses - 3 Double Convex, 3 Double Concave - 38mm Diameter - 20, 30, 50cm Focal Lengths

(3) Double Concave -20,30,50cm Focal Length, (3) Double Convex - 20,30,50cm Focal Length

This lens set is perfect for doing optical experiments comparing focal lengths and convex vs. concave lenses.