(Attachment Unit Interface) The AUI is the 15-pin physical connector interface between a computer's network interface card and an Ethernet cable. On 10Base-5 ("thicknet") Ethernet, a short cable is used to connect the AUI on the computer with a transceiver on the main cable. In 10Base-2 or "thinnet" Ethernet networks, the NIC connects directly to the Ethernet coaxial cable at the back of the computer. The interface of a Kaba Benzing Ethernet adapter BETA consists of an AUI and an external transceiver.