Doorbird RFID Fobs and Cards Doorbird $10.00 Fob - $10.00 Card - $10.00 Quantity This variant is currently sold out Please fill in the form below if you'd like to be notified when it becomes available. DoorBird 125 KHz Transponder Key Fobs and Cards, 64bit, write-protected, material ABS, for D21x and later work flawlessly with all Doorbird RFID equipped readers.