This part of IEC 61076 describes M12 circular connectors typically used for industrial process measurement and control. These connectors consist of fixed and free connectors either rewireable or non-rewireable, with screw-locking. The connectors with glass to metal seal are fixed connectors only which consist of fixed glass to metal sealed styles with rewireable male contacts and are intermateable with corresponding free connectors according to this International Standard. Male connectors have round contacts ∅ 0,6 mm, ∅ 0,76 mm, ∅ 0,8 mm and ∅ 1,0 mm.

The different codings prevent the mating of these coded male or female connectors to any other interfaces and cross-mating between the different codings.