The Ulanzi Action Camera GoPro 9 Metal Cage is a metal case that allows you to enhance the video and audio quality of your GoPro Hero 9 Black for a more professional shooting experience. It features a removable base for a microphone or light, as well as a removable base for a filter. The microphone base connects to the bottom of the metal case and provides a slot for installing an optional GoPro 3.5mm microphone base. It can be mounted on tripods, monopods, and other supports.