Note : Key fobs are blank, with no data inside, cannot directly add them to a RFID lock!!! Must write data to them by a 125KHz RFID card writer first. | Read and Rewritable : RFID key fob with rewritable chip, and it can be used in 125KHz RFID card Copier/ Writer. | Frequency : 125kHz. T5577 key fob is suitable for making new and back-up tags, can be erased and written 100,000 times. | Material: The key tag is made of ABS, waterproof and environmental material. Each package includes 10 PCS. | Sweet Service : If you have any questions with our product, please contact us and we will try our best to make things right.