Baader Solar Filters provide a professional and secure solution to observe and image the Sun using AstroSolar Safety Film OD 5.0. Many ready made filters do stretch the filter material like a drumhead in order to make it look like a piece of glass - this absolutely does destroy the image quality, rendering the film useless for high magnification work. AstroSolar must be mounted entirely stress free in order to perform like a high precision plane optical window. It sounds like a contradiction with traditional perception of quality, but AstroSolar must show slight ripples! Only when the film is being put under stress by an improper cell mount it performs just like any single side coated glass-filter made of untreated float glass. This Filter is suited for observation of the sun with binoculars (two piece needed) and camera lenses. The AstroSolar filter material is mounted onto a plastic ring whereas the plastic ring itself works as stabilizing element for the filter cell. This still plastic ring is mounted onto the aluminium front frame. The only difference is that one side is cut off in order to make them usable on any binocular - even when the bridge is nearly closed. (depending on the binocular type).