Similar to SDI-B4 Link but the ETH-B4-LINK-V1 data input is via network instead of SDI. The protocol is also Blackmagic Camera Control, but over UDP ("UDP Camera Control") and typically served by a SKAARHOJ controller. It has an incredibly light and compact form factor.
With the SKAARHOJ ETH-B4 Link the iris control data is sent separately from the camera control data over Ethernet instead of over SDI. The ETH-B4 Link has a camera selector switch that sets it's camera ID filter as well as its IP address and the iris data it receives is output on the Hirose-12 connector. It also features a tally lamp (red/green) and a relay output (PGM tally out).