The RFiD Card 125KHz is based on the EM4100 Manchester & Bi-Phase encoding device.
The EM4100 (previously named H4100) is a CMOS integrated circuit for use in electronic Read Only RF Transponders. The circuit is powered by an external coil placed in an electromagnetic field, and gets its master clock from the same field via one of the coil terminals. By turning on and off the modulation current, the chip will send back the 64 bits of information contained in a factory pre-programmed memory array.
It is ideal for logistics automation, anti-counterfeiting and access control.