optical prism 1.materials:K9,BK7,B270,H-K9L. 2.ensure product quality. 3.low price. optical prism Colorless Optical GlassK9, BK7, B270There are colorless optical glass K9, BK7, B270, etc. of several, mainly for a variety of coated substrates, window film, airport lamps, optical apparatus, instruments and other fields. optical prism