The Formatt 6.6 x 6.6" UV 2A Haze optical filter in Schott-Desag B270 Crown glass is a sound investment. It can help protect your precious investment from dust, moisture and scratches, which can lead to costly repairs. It provides virtually 100% UV absorption. The Haze 2A is excellent for conditions where UV is very present, such as at high altitude. - If desired, it can be left permanently on the lens for continuous protection - Haze filters offer additional correction benefits for ultraviolet (UV) light which can register on film and videotape as a blue cast and can obscure distant detail - Ultraviolet filters allow you to correct the UV effect to varying degrees