Anand traders 18mm plano convex lens with 31mm focal length for DIY telescope eyepiece experiment : Amazon.in: Electronics
10pcs x high Power 20MM LED Smooth Convex Lens - - Amazon.com
EISCO High Quality Glass Lenses, Set of Four, Double Convex & Concave Lenses of Dia. 50 mm, Polished, High Quality : Amazon.in: Industrial & Scientific
Optical Concave Convex Lens Prism Set Physical Optical Kit Laboratory Equipment Suitable for School Optics Education : Amazon.ca: Industrial & Scientific
RG® High Quaity Lens and Mirror Set| Set of Concave, Convex Mirror and Concave, Convex Lenses. 50mm diameter,Focal Length-20 cm : Amazon.in: Industrial & Scientific