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.
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.