Part of our educational optics series. Double convex, spherical glass lens, with a focal length of 300mm. Made of glass with polished face and ground edges. Refractive index is approx. 1.52. Unused and individually boxed. Perfect for educational projects, but focal length is not in close tolerance from lens to lens, so not good for use in a product you are going to manufacture where the focal length needs to be exactly the same.