Nuvotech NuvoLink II Nubus Network Card for Macintosh with 10base2 (Thin Coax) and AUI ports.
Note that thin ethernet networks require termination with a 50ohm BNC terminator at each end of the chain (unless the last node is an Apple AAUI transceiver which self terminates).
Driver software may be required (not included). It may not be compatible with the Centris/Quadra 660AV but can be used in any other Macintosh with NuBus slots.