What kind of battery is used for the transmitter CDT-TX-02M-R 434 MHz?

The CDT-TX-02M-R 434 MHz is designed for battery operation. If no inputs are triggered, the transmitter will go into stand-by mode where the current consumption will be decreased down to approx. 1uA. The current consumption during transmission is 27mA. Since there are no pauses in transmissions (i.e the internal RF circuit is on continuously as long as inputs are triggered), it is recommended to use 2 x AAA batteries (3V) and not a coin battery.