Set of 6 unmounted spherical lenses to explore the properties of different lenses, how they interact and affect light, concepts of reflection and refraction and combination of lenses. Made of optically worked plate glass with polished faces and ground edges. Includes one each of the following typical shapes - double convex, plano-convex, converging concave-convex (convexo- concave), diverging concave-convex (concavo-convex), double concave and plano-concave. Supplied in a velvet-lined box