The Cokin S Filter A121M Gradual Neutral Grey G2 Medium (ND4) is a high-quality lens filter specifically designed for photographers who seek precise control over the exposure of their shots. This screw filter belongs to the category of Neutral Color Filters and allows for a uniform reduction of the amount of light hitting the sensor, without affecting the color balance of the images. With a thickness of 4 millimeters, this filter is ideal for various lenses and offers a gradual gradient that is particularly useful for emphasizing the sky in landscape photography or balancing contrasts between the sky and the ground. The exact color designation "Neutral Grey" and the color group "Grey" ensure that the natural colors in your images are preserved. The filter is a valuable addition to the equipment of photographers working in both digital and analog photography.