Frequency Range : TX 136 - 174 MHz RX 136 - 174 MHz Mode : F3E, F2D Antenna Impedance : 50 Operation Temperature Range : -20 C ~ +60 C Operating Voltage ; DC 6.0 ~ 9.0 V (Standard Voltage DC 7.4 V) Frequency Stability : 2.5 ppm Microphone Impedance : 2 k Battery Life* (Figures approximate) : High / Mid / Low with KNB-63L : 6 / 8.5 / 10.5 Hour with KNB-65L : 8 / 11.5 / 14 Hours with BT-16 : 6 / 8 / 10 Hours Dimensions : (W x H x D),