Neutral density filter, used to filter light. Apply slow shutter speed under strong sunlight exposure. | Control the amount of light in the 1 to 9 stepless adjustment. | The outer ring can adjust the gray level arbitrarily, and can be transferred from ND2 to 400. | Filters are great for removing unwanted reflections from non-metallic surfaces and increase contrast and color saturation. | Package included: 1pc x ND filter 1pc x storage bag.