this photogrey PGX properties flat lens is designing for the Camera or Industrial Camera, and it is Chemically Tempered, Polished edges, the quality is super higher.
material : PGX optical glass Diameter: 65.0 mm +/- 0.1 mm Thickness: 4.0 mm +/- 0.1 mm Finish: Chemically Tempered, Polished edges
the surfiace is smooth, chemically tempered, polished edges.