N1635-F Focus Gear ~for AF-S NIKKOR 16-35mm f/4G ED VRFocus gears allow access to the mechanical zoom function of many lenses. Use of these gears may require specific port extensions and may not be available for all housings and lenses. This focus gear is specific for the AF S NIKKOR 16 35mm f 4G ED VR lens. This item is non returnable, non refundable, non cancellable, and may be subject to extended lead times as it is manufactured on demand. We always do our best to meet trip deadlines so please advise