The Aquatica 30600 Port Extension Ring is for their AN series underwater housings for Sony NEX cameras. Insert the ring between the port and the housing to add 0.65" to the length of the port. The extension ring is constructed from durable anodized aluminum.
To check lens and lens port compatibility, please see the following chart:
Sony Type 1 Lens Chart
30600 Port Extension Ring for AN Series Underwater Housings
1 Year Limited Warranty for Consumer Use, 90 Days for Commercial Use