RFID TAG 125kHz EM designed as Keychain, Waterproof, Durable, Gray

The most frequently used 125 kHz transponders - also called tags - are of the "read only" type - ie. They are provided with a unique ID code of up to 40 bits, which can not be changed. Tags are available in a variety of different designs. Eg. round pieces in different sizes and formats, like keystrokes and credit cards. Only the most popular types are shown here.