NOTE: These are 125kHz cards (labels). If you want to add them to your lock system, make sure your system uses the same unencrypted frequency of 125kHz. Not compatible with other frequencies such as 13.56MHz. Not compatible with cryptographic tags such as HID, Indala, Cobra, APCiK, Paradox, Radio, Honeywell, Kaba, Isonas, etc. Read only. Not overridable. You can't reprogram them. Each card is pre-programmed with a unique ID number. 10 digits are printed on the card. Compatible with other common 125kHz Chip: TK4100 Application areas: access control, elevator, attendance and patrol systems Card reading distance: 2.5-10cm (related to the card reader) Suitable for 125kHz RFID proximity access control systems and ID management systems. For example, if applicable, add them to your RFID door locks as new key fobs. Card size: 85.5*54mm Shell material: PVC plastic. Package includes 100 pieces.