Use this Sea & Sea Zoom Gear to control manual zooming with your Nikon AF-S Fisheye NIKKOR 8-15mm f/3.5-4.5E ED lens in a compatible lens port, which mounts onto an MDX underwater camera housing. For compatibility, see the MDX System Chart. Manual focus cannot be used when this zoom gear is in place. The gear mounts onto the zoom ring of the lens and is controlled via the focus/zoom dial/knob on the housing. It is constructed from a corrosion-resistant aluminum alloy.