A cardholder Access Control credentials are carried by the user and contains a unique code that is made up of the site code and card number

To access a door or portal. the credential is placed near to the reader so it enters the field of the antenna and can pass its contained number back to the reader. The size of the readers antenna will determine how close the credential needs to be placed
Within the credential is a loop of wire with a chip that contains the site code and card number. Once in the field of the reader antenna. the card is powered and transmits its numbers back to the reader
Credentials are available in many forms with the most typical being the access control card
Access control cards are similar in appearance to that of a credit card with dimensions of 5.4 x 8.57 x 0.084 cm
Another option for an access control card is the clamshell which is thicker and used in harsher environments. A clamshell card‘s dimensions are around 5.2 x 8.57 x 0.18 cm.
Cards can be ordered with or without lanyard cut-outs as well as other options including barcode, magstripe. or, with different technologies contained within the same card.
Card production companies do offer printing services so cards can be pre-printed with company information or layouts, however it is not possible to print on Clamshell cards.

It is vital to the continued correct operation of the access control card that no damage occurs to its integrity.
Normal causes of failure for these style of cards include
Manual Hole punching to create a lanyard hole and thereby breaking the wire loop
Excessive bending of the card thereby breaking the wire loop
To protect this style of card, plastic covers are available that offer lanyard holes as well as providing a non-flexing storage device.
Access control cards that support more than one technology are used in multiple applications .
A magstripe on the rear of an access control card can be encoded at the customers site with a non-secure number that can be used in different applications e.g. library

A real benefit to cards that support multiple technologies is when sites are being upgraded and readers replaced with a new technology, the multiple technology card is able to be read by both the old and new reader
Alternatively an organization might have two different reader technologies within its estate and a card that supports both technologies means the cardholder only has one card to manage
Another form of cardholder credential is the tag. A tag offers the user the benefit of being able to be carry the tag on a key chain or stuck onto another item e.g. Mobile phone

In the case of a system upgrade of reader technology the tag allows the site to issue the second, i.e. newer technology, to the cardholders’ without issuing a new set of cardholder credentials
The tags, like the cards, offer the user the ability to access other systems including cashless vending and network security