The Polar Pro DiveMaster 3-Pack Filter Kit for GoPro HERO9 Black includes three filters for diving in blue, green, and shallow waters. The filters are designed to attach to the Protective Housing for the HERO9, so this additional accessory will be required, and they attach by a secure slide-on design with added safety tethers that ensure your filters stay connected in all diving conditions. The filters allow you to capture accurate colors by compensating for underwater conditions. The included red filter performs best in blue waters at depths from 15 to 75'. The magenta filter is for green waters at depths from 15 to 75'. And the snorkel filter is designed for shallow waters 2 to 15' deep. A hard-shell protective storage case is also included that holds all three filters. The filters are built with an optical polycarbonate lens and are lightweight, rugged, and durable.