Extension Ring 46 with Focus Knob provides a manual focus for compatible zoom lenses. (Extension ring equipped with port lock).

Compatible Housings:

• MDX series housings.

Compatible Lenses:

• Canon EF 16-35mm F2.8L ll USM,
• Canon EF17-40mm F4L USM,
• Nikon AF-S Nikkor 18-35mm F/3.5-4.5G ED,
• Nikon AF-S Nikkor 16-35mm F/4G ED VR(as of June2014).

* Compatible FC focus gear required for manual focusing (can be used in conjunction with a compatible zoom gear).