This Kraken Sports Red Filter V2 is designed for use with the Kraken KRH07 and KRH08 underwater smartphone housings (not included) and will not work with other housings. Made from polycarbonate, the filter is extremely strong and resistant to scratches and cracks. It slides into the accessory track of the housing. The deeper you dive (the housings support depths up to 280') the more red wavelengths are removed, resulting in a blue cast to your images that can be difficult to remove. The red color of the filter balances out the blue cast that you can get when shooting underwater, which makes it easier to color correct in post.