Used for industrial ethernet and EtherCAT.

Round M12 connector (same shell / thread as NMEA2000).

Variants with 2 or 4 pairs.

“Coding” means the plastic tabs / keys to only allow correct connectors to mate.

• D-Coding according to IEC 61076-2-101. 2 pairs, 100 Mbps
• X-Coding to IEC61076-2-109. 4 pairs, up to 10 Gbps.

Up to 500MHz bandwidth/Cat 6a

Can carry PoE.

Parts seen on aliexpress. Cable gland type fittings that go on cables both sides of an RJ45 coupler.

Also seen some on aliexpress.