SEOH Lens Glass Double Convex 50mm x 1000mm Focal Length
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SEOH Lens Glass Double Convex 50mm x 50cm Focal Length
Ajax Scientific Polished Glass Double Lenses Spherical (Bi-convex), 50mm Diameter, 50mm Focal Length
Eisco Labs 6 Piece Premium Optical Glass Lens Set, 50mm Diameter - 3 Double Convex (20, 30, 50cm FL) and 3 Double Concave (20, 30, 50cm FL)