A buckle, such as a vehicle seat belt buckle, operable between a buckled and unbuckled condition. A sensor integrated circuit in the buckle senses the buckled or unbuckled condition of the buckle and generates an electrical signal indicative of the buckled or unbuckled condition of the buckle. A RF integrated circuit in the buckle and in the form of a microcontroller integrated circuit with an RF signal transmitter receives the electrical signal generated by the sensor integrated circuit and transmits an RF signal indicative of the buckled or unbuckled condition of the buckle to a vehicle's control unit via an RF signal antenna in the buckle. A battery in the buckle provides power to the sensor and RF integrated circuits.