We use acetate, stainless steel, metal and titanium for our frames. The material used for a specific frame is indicated on its corresponding product page. We do not offer Polycarbonate frames as these are of inferior quality to acetate, for example.Our prescription lenses are made from a quality resistant plastic called CR-39. This material is an industry-standard used by even the most expensive opticians. Lenses are customised in our laboratories to make sure they accommodate the prescription you have indicated. They are coated with anti-reflection and anti-scratch layers for free.It is good to know that our lenses come in different indexes ranging from 1.61 to 1.74. The higher the index, the thinner and more costly the lens will be. The default index for our lenses is 1.61, which is a thin lens according to industry-standards.The standard demo lenses that come with the frames-only option are made of Polycarbonate, which is a thin and durable material.