The Formatt clear filter is a clear (colourless) filter for colour and black and white film. It also serves as permanent protection for the lens.nnn- Each filter is manufactured from Schott-Desag B270 Crown optical glassnnn- Absolute consistency in colour and density according to Kodak Wratten standardsnnn- Precision grinding and polishing provide unbeatable optical flatness, allowing use even on very long focal length lensesnnn- The filter edges are protected by a unique frame for maximum protection and easy handling