The use of a neutral density filter is that it allows the photographer to better control the shutter speed and aperture size to achieve certain special effects in various environments (especially when the light is strong) without causing overexposure due to a slow shutter speed. | Size: 3.22x3.22 inch; Photo Filter Thread Size:82mm; Color:Black; Material: Optical Glass, Aluminum; Packing List:1 Pcs ND2-400 Lens Filter | In landscape photography, ND Filter is widely used. It can make waterfalls look as smooth as silk, turn ocean wave into elegant sea of clouds or dreamlike silk, express the dynamics of clouds vividly, and connect the lights of cars in the city into flowing light trails. | When installing the ND filter, please note that the ND must be inserted on the side closest to the lens, and it should fit the frame as closely as possible.The Variable ND Filter easily switches from ND2 to ND400 to reduce light intake (1 to 8.66 f-stops) and maintain even color balance. | Ensure a perfect fit by verifying your camera's lens thread size before ordering. The lens thread size is indicated by a "Φ" (diameter) symbol followed by the size, such as Φ95=95mm lens thread size.