The Leica E49 UVa Glass Filter is used to safeguard your lens from dust, scratches, and moisture.This polarizing filter can avoid disturbances caused by the Ultraviolet light rays by correcting it at any degreeThe Leica UV filter is ideal to be used while shooting in misty mountains and marine environments to prevent bluish cast and blurred imagesYou can remove the filter when not in use or leave it on the lens for all time protection