United Scientific Supply Double Convex Lens, Glass, UNMOUNTED, 75MM Dia / 100MM FL, Each - USS: Amazon.com: Industrial & Scientific
Plano Convex Lens, 50 mm Dia, 100 mm FL - Glass - Eisco Labs: Amazon.com: 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