Just what it says on the tin--three filters that reduce haze in different types of underwater environments for Sony full frame Alpha cameras. The orange and red filters are for blue sea water of varying depths. If I remember correctly, the orange is for shallow depths of less than 10 feet with the red filter for deeper water. The purple filter is for greenish sea water or fresh water. They clip onto the camera meaning you don't have to do anything with the water housing. It also gives you another layer of protection over the camera sensor and that's never a bad thing. All with the usual high quality Kase materials and multicoated glass. Recommended!