The Visionis proximity cards (or access cards) are hybrid technology that incorporate a simple electric circuit (proximity tag and coil) embedded in a plastic card. No battery is needed and the circuit is not removable without destroying it and the card. When the card is correctly positioned with respect to a reader a high speed RF signal passes between card and reader and unique data is transferred. This ISO standard proximity card is 1.8mm thick and can have printed material attached to the front. It is supplied with a pre-assigned unique code and the cards are 125khz.