Gary: great for removing unwanted reflections from non-metallic surfaces, such as glass or water. Mounted on a rotating frame, this filter can be adjusted to block different levels of reflection. This filter is designed for diving fans who like taking photos and videos under water for Gopro 3+4.Due to wave refraction, pictures taken underwater may suffer color distortion.Using this color correction filter, pictures taken under water will be more lively and natural.Directly use on the Waterproof lens cover ,very convenient. High Quatily Grey Underwater Diving UV Lens Filter for GoProHero3+ 4 (For 40m Housing) Color: Grey Model No.:GO89GR Specifications: Type: Lens Filter Suit for: Gopro 3+ 4 Item size: 5 * 5.3 * 1.2cm / 2.0 * 2.1 * 0.5in Item weight: 15g / 0.5oz Brand No Brand SKU OT776EL0Q9A3CNAFAMZ-37701 Model GP89GR