Industry standard 125KHz RFID technology 26 bit Wiegand format Non-contact reading for long life Use with the Viking PRX-1, PRX-2, PRX-3, PRX-5 or certain legacy 125KHz HID proximity card readers PRX-C is a durable 0.070 thick plastic card with a slot for neck strap PRX-C-ISO is a thin 0.032 thick flexible ISO style card PRX-FOB is a durable key ring fob with a IP67 rating allowing it to even withstand the washing machine Up to 253 facility codes and 65,534 card numbers available Cannot be erased by a magnet