Nauticam N100 to N120 40mm port adaptor w/ zAn adapter to convert from an N100 port opening to N120 port opening for the Sony A7 system. The extension also has an integrated focus zoom gear knob. See Port Chart for more details on choosing the correct extension and port. Technical Specifications Depth Rating 150m Port System N100 to N120 Conversion Weight Port Opening Diameter Port Diameter Body Material Anodized Aluminum Alloy Port Material Port Coating Port Shade Material Removable Port Shade