With this Light & Motion 65 Wetmate Caddy, you can secure your Fathom 65 Wetmate Lens to the top of your Bluefin housing for camcorders when it's not attached to the housing's port. Mounting the lens atop the Bluefin allows you to access it quickly and easily in shooting situations that call for a wider angle of coverage. A stainless-steel mounting screw is supplied.