New, boxed, original Apple EtherTalk NB NuBus network card with 10base2 (thin/coax) and AUI outputs, including sealed software (EtherTalk Installer ver. 2.0 floppy disk) and documentation pack. The box is very tatty.
It may not be compatible with the Centris/Quadra 660AV but can be used in any other Macintosh with NuBus slots.
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).