Digital SIM spy voice recorder, spy anyone in any place, place a SIM card in this spy device, call this number, this spy voice recorder will auto answer, dimensions 39 x 12 x 27 mm, 24 hours non-stop power supply, all GSM SIM card compatible, microphone range 5 - 7 meter - 4 levels, receive sensitivity -+10K, working temp 40 - 50'C, responding frequency 1.2K~800Khz, stand-by time 10 days, working time 4 hours.