W have more that 100 types of fobs, with 2 or 4 buttons, even though we have fobs until 48 channels; with proximmity system included. Our fobs get some advantages to others. We weorks with 868 Mghz frecuency that give you more opening distance and work.
The sended code is eviolutive, so it change for each pushing to avoid illegal copy.
Each fob has an unique serial number, so we could know who is its user, and it could be program without desplacement.
Also, we could delete fobs without desplacement and cost to community becuase a replaced fobs could delete the stolen or lost fobs.