M12 A-Code Circular Connectors Stewart Connector/Bel M12 A-code Connectors include both male and female panel-mount receptacles and field-terminated plug options. The four- or five-pin option connectors are ideal for use in industrial automation, outdoor applications, measurement and control, agriculture, and more. A-Coding (or keying) within the M12 series prevents mismatching with other M12 coding/keying options. The Stewart Connector/Bel M-12 A-code connectors have an IP67 rating when installed, allowing a reliable connection in an industrial environment. IDC and soldering termination options offer quick and easy installations, replacements, or upgrades.