This focus ring is specifically designed for the #36162 Nauticam port. Rather than using the external knob on the port to switch from macro to e-zoom, this ring allows manual focus. Zoom is still available either by using our other zoom ring (in electric or mechanic zoom mode) or by assigning custom buttons to zoom in and out when the zoom is set to electric. Due to its closeness to the port, it is only available in dark color to avoid reflects on the images.