RF proximity card.
Automatic user identification by RFID. Passive card, when in proximity to the reader is activated by magnetic induction. When activated (electromagnetic induction) it returns a code to the system so requires no battery.
Communication with the reader is with a 125KHz low frequency radio antenna.
Manufactured in PVC and with a similar size to most credit cards so can be transported in most card wallets.
Pack of 50 cards