Provided by ABS material packaging chip and coil and fill them with epoxy resin, ultrasonic welding combination with all sorts of modelling of key rings card
Different colors are available 
Internal can encapsulate the different versions of the high/low frequency of chip
Surface can mark icon, SN
Have dustproof, waterproof, shock resistant properties
With key ring buckles, easy to carry
Applied to door, attendance management, transportation, parking, one-card payment, etc