Apple’s FriendlyNet 10BASE2 ethernet or thinnet networking.
This M0329 transceiver, with it’s 4 foot cable, plugs into the AAUI ethernet port on your Mac. Coaxial cable is then used between two or more transceivers to network computers and printers. If Apple’s coaxial cable is used, no BNC T-connectors or terminators are required. The transceiver will automatically terminate the network if a cable is not attached to one side. The Apple 10BASE2 coaxial cables will also terminate the network if no device is attached them.
The transceiver can only be used with a Mac or Apple device (eg printer) with an AAUI ethernet connector.
The AAUI ethernet port was introduced with the Quadra 700 and 900, it was a standard port on most Macs until discontinued with the G3. Some PowerBooks and LaserWriters also have this port.