Single button (1 channel) visor clip transmitter for the LIN-REC. Black case with gray button. Powered by 2-3V DL-1616 lithium batteries (included). 318MHz transmitter frequency. Individually numbered at the factory with random code numbers. Dimensions: 1.6" W x 4.2" H x .8" D (4.064cm W x 10.68cm H x 2.032cm D).