By mounting this Zoom Gear from Fantasea Line onto the zoom ring of the Sony E 10-18mm f/4 OSS Lens, you'll enable focal length adjustments when the lens is inside the FML Dome Port A6 with Port Extension 25. This port is compatible with Fantasea underwater camera housings that have FML mounts, including the FA6500 enclosure for Sony's Alpha a6500 and a6300 models. The gear connects to the housing's lens dial, which can be turned for smooth, seamless operation of the 10-18mm's zoom function. Be sure to use auto focus, as the focus ring of the lens will not be accessible via this gear.
Fantasea Line Zoom Gear for Sony E 10-18mm f/4 OSS Lens in FML Port