This Port Extension Ring with Focusing Knob from Aquatica is for the Canon EF 16-35mm f/2.8L II zoom lens when used within an Aquatica lens port. It extends the length of the port by 2.93". Optimized for the 9.25" (23.50 cm) Megadome port, it can also be used with the 8" dome port. It has a manual focusing knob that connects to the lens' focus ring via a gear. This knob has a retractable mechanism that makes installing and removing the lens quick and easy. The extension ring features anodized aluminum construction and a depth rating of 300' (91 m).
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