The Zoom Gear for Sony 18-55mm Lens from Amphibico enables zoom control when the lens is inside a compatible port connected to the Genesis FS100 underwater camcorder housing. It is designed for use with the Aquatica #18405 8" dome port with the #18457 extension or the #18407 9.25" dome port with the #18458 extension. The gear enables access to the full zoom range of the lens. It mounts on the zoom ring of the lens and connects to the housing's zoom control knob. Manually rotate the zoom control knob to move the zoom back and forth while shooting.