Liner, I think the orinigal you gotta get from Nissan, you have to give them the pin number as well which can be found in your original owners manual (if u have it) and they will supply you with a new key, coz the little red square you see on the key is actually an immobilizer/anti-theft device, so it must match your ignition sensor in your car.
If you dont have the pin code, better not loose your key!
Btw, i think your spare keys does also have the red thingys attached, and it may be possible to transfer one from your spare to a future new key... or some people have been known to remove the red thingy from their keys and fitting it inside the ignition permanently, just in case they loose their keys as they have made duplicates locally. But then by doing that, you have disarmed the factory immobilizer.
Hey Remus, do you know where to get the taillamps/rear lights, not just the bulbs/LED housing but also the outer housing?