This pack of 100 clamshell 37 bit proximity cards seamlessly integrate with HID H10303 37 bit proximity access system. On top of working perfectly with your current proximity access program, all UltraSecure cards are more cost effective than their HID counterpart, ship extremely fast and come with a lifetime warranty. Clamshell cards are thick and cannot be sent through an ID card printer. Print on an adhesive card and then stick it onto the front of the clamshell. This allows for re-using the encoded clamshell card.