HYS TC-M10W Dual Band VHF/UHF FM Transceiver 136-174/400-490MHz 10W Mobile Transceivers Dual band:TX&RX 136-174MHz/400-490MHz;High/Low power (10W/5W);Channel steps (2.5K/5K/6.25K/10K/12.5K/25K); Dual Reception/Dual Display 128 memory channels; To operate DTMF function you can input DTMF code from microphone keyboard , the function is similar other radio or phone DTMF key . Our radio can submit 8 groups DTMF groups for storing. Operating Temperature:-20 ~ +60 (-4F ~ +140F);Operating Voltage:DC 13.8V +7% ~ -15% Remark: Negative Grounded Scrambler :An analog voice inversion scrambler can be equipped as optionals.This special audio process can offer a more confidential communication. Other radios at same frequency will be receive only disordered noise .Voice Compander :Enable this function to reduce background noise and enhance audio clarity ,especially in long range communication .