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IEC 61076-2-106 Ed. 1.0 b:2011
"Connectors for electronic equipment - Product requirements - Part 2-106: Circular connectors - Detail specification for connectors M 16 x 0,75 with screw-locking and degree of protection IP40 or IP65/67"
"IEC 61076-2-106:2011 describes circular connectors with IP40 or IP65/67 protection degree, typically used for industrial process measurement and control. These connectors consist of fixed and free connectors, either rewireable or non-rewireable, with M16 x 0,75 screw-locking. Male connectors have round contacts + 1,5 mm or + 1,0 mm. "
International Electrotechnical Commission [iec]