Do not buy second hand keys !!!!!!
Alfa romeo keys are specific to the car so second hand key fobs cant be used!
Unless you get along with it......... The immobiliser box and the ecu.
If you own an Alfa and have lost a key recently you know how expensive it is, but dont throw money after bad items trying to save a few quid.
I have recently done the wife's car so know how much you need to get it to work.
A key, transponder ring, ignition barrel and immobiliser box is useless without the ecu as they are linked and specific to the car.
Ideally you should go for a full set of locks, ecu, immobiliser box and alarm/central locking receiver all with a linked key and curcuit board inside.
You can however get a Blank key fob get it cut to your locks and swap the innerds including transponder chip.
If you need more specific advice you can message me through ebay. Dont get conned !!!!