High quality import Germany Glass, 18 layer coating, high definition and scratch resistant. Only 7mm thickness ultra thin frame, avoid dark corner. Aluminum material, very lightweight. Allows for variable light reduction from between 2-8 stops; protect your lens from dust and scratches. Decrease the depth of field by using wider apertures, which helps separate subjects from their background. Allows the use of slow shutter speeds, with high speed films or digital cameras, to record movement/image blur in subjects such as waterfalls, clouds or any fast moving subject.