Proximity cards (or access cards) are hybrid technology that incorporate a simple electric circuit (proximity tag and coil) imbedded 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. Range: 10cm-15cm (3.94″-5.91″) Can bear printed material ISO standard spec 1.8mm thick Each card has a unique pre-assigned code (8 digit number) printed on the back. 25 pieces per pack