Takes the DCC signal from your existing command station and puts it on the air to be picked up by the receiver(s) in your locomotive(s) (see above). Simply connect to the back of your command station to the rail outputs and place in the center of the room near the ceiling. Use twisted pair or speaker cable for long runs (> 10 ft) back to the command station. Since the transmitter only draws 21 mA, the wire can be as small as 28 ga. Only one transmitter is needed for the entire layout. This device transmits low power radio frequencies on the Instrument-Scientific-Medical (ISM) band with a range of about 50 feet.
The new MKII version is smaller and more compact. Dimensions are 79mm (3.125") 20mm (0.812") long by 15mm (0.635") thick. Input: DCC 5-30V peak-peak; uses 21 mA (.02A). Ouptut -4.3 dBm 868 MHz.