Helps control exposure and/or add motion blur in bright environments Reduces light by 1 stop Compatible with Pro Series Macro Lens Compatible with Beastgrip Pro and Beastcage for iPhone with a 58mm lens filter adapter (not included) Improve exposure in bright environments without having to increase your shutter speed or frame rate as much. This allows you to get more interesting effects like motion blur and shoot long exposure photos without overexposing your images/videos. Think of these as “sunglasses for your camera,” and the higher the number means the higher the light reduction. The 58mm filter is compatible with our Pro Series Macro Lens and can also be used without lenses when mounted to the Beastgrip Pro or Beastcage with 58mm adapter mounts. Note: 58mm filters cannot be mounted directly to our Pro Series Lenses with a 62mm filter mount. We recommend using 77mm filters with the included 62-77mm step-up ring, which comes with our Pro Series Lenses.