ND4 filter - This filter is designed to cut light from falling on the sensor by 2 f-stops, making it ideal for filming in cloudy daytime conditions.This filter effectively helps to smooth out the footage by slowing down the shutter speed of the camera. ND8 filter - This filter is helpful for reducing light from entering the lens by 3 f-stops, which is best for photography in partial cloudy daytime condistions. This filter also helps to reduce the lens flare from the sun effectively to give crystal-clear images. ND16 filter - This filter is used to cut light entering the lens by 4 f-stops, which makes it best-suited for filming in normal sunny conditions. This filter is helpful to get natural-looking blur in the footage while filming outdoors.Lens Filter: ND4 / ND8 / ND16 Frame Material: Aviation Aluminum Alloy; TPU&PC Lens Material: Optical Glass; Multi-layer Coating Frame: Ultra-thin FramePackage Included: 1x ND4 Filter 1x ND8 Filter 1x ND16 FilterHow to use:You have to remove the lens on the camera and put the filter lens on it instead.Remove lens with counterclockwise twist 45-degrees, then reverse procedure to put on filter lens.Replace with filter lens rotating 45-degrees clockwise. Disassembly1. Twist lens counterclockwise as far as it can be pull out.2. Take off the lens outwards(Pulling lens slightly is required when Twisting the lens left).Installation1. Prominent cylinder with waterproof ring on the lens should be aimed camera solt.2. Turn the lens right, two silver steel needles on the left and right side should be stuck on the camera(Two silver steel needles on the lens should be staggered with the slots on the left and right side of front lens).