This part of IEC 61076-2 describes the bayonet coupling interface of circular connectors that are typically used for industrial process measurement and control. These connectors consist of fixed and free connectors either rewireable or non-rewireable, with bayonet-coupling. These connectors may have glass to metal seal inserts. They have male or female contacts and are deemed be intermateable with corresponding free connectors produced according to this International Standard. Male connectors have round contacts Ø 0,6 mm, Ø 0,76 mm, Ø 0,8 mm and Ø 1,0 mm. Differing coding’s shall prevent the mating of these individually coded fixed connectors (and consequently of individually coded free connectors deemed to bayonet couple with them) to other interfaces and cross-mating between the different coding’s. However, the styles and interface dimensions, except for the coupling mechanism, shall be as given in of subclause 4.3 of IEC 61076-2- 101:2012 and subclause 4.3.1 of IEC 61076-2-109:2014. The male type B12 circular connectors shall be interoperable with the female type B12 connector of the same coding and ways. The female type B12 connectors shall be interoperable with the male type B12 and M12 (threaded screw coupling) connector of the same coding and ways. NOTE – B12 relates to a bayonet coupling with tube dimensions compatible with a M12 thread. M12 is the dimension of the thread of the screw-coupling mechanism of circular connectors covered by IEC 61076-2-101 and IEC 61076-2-109, which provide the mating interface (connector insert level) to these connectors with bayonet coupling.