Description:
Frequency: 125KHz; Chip: T5577 (compatible with other universal 125KHz tags).
Writable & Rewritable: It can be erased and written 100,000 times. Suitable for making new and back-up tags, with the 125KHz RFID card writer/copier.
You cannot add them to RFID locks directly. You must write data into them by a 125KHz RFID card writer before use.
They are blank tags, no data inside.
Can write by 125KHz RFID writer/copier, need to write by RFID writer.
Not NFC chip, can't work with NFC phone.

Specification:
New and high quality
Product name: 2 # ID key chain
Chip type: T5577 chip
Working frequency: 125KHZ
Product size: 35 * 27.5 * 4MM
Working temperature: - 40-55 ℃
Packaging material: ABS, PVC
Sensing distance: 2-10CM (depending on card reader)
Scope of application: access control/attendance/elevator/parking, etc
Product color: random
Package Included：2Pcs

Note:
Please refer to the measurement. Tiny measuring error is allowable in normal range.
As different computers display different colors, thank you for your understanding, the actual product color may be slightly different from the image.