The GSM micro is REALLY the smallest GSM audio infinity transmitter in the world. Thanks to its ultra-miniature dimensions (1, 8"x1, 4"x0, 4"-4, 5x3, 5x1cm) it can be concealed almost anywhere for surveillance and security monitor of your premises. This super miniature GSM transmitter can actually work WORLDWIDE under any GSM-based cellphone network (900 / 1800 / 1900Mhz) including USA. Extremely easy to operate and deploy, the GSM micro can be totally remote controlled by using any GSM-type cellphone or even landline touchtone phone. 3 different product versions are available: 1) battery powered: uses commercially available AA or AAA batteries and / or rechargeable miniature battery pack (please specify upon ordering) ; 2) 12Vdc car battery powered: for installation on any vehicle and continuous operation; 3) 110 / 220Vac mains powered: for installation on any mains power network and continuous operation. All versions feature: * remote control of all features via SMS protocol * unlimited operation range thanks to the GSM cellular network * password-protected access * multiple user access * two preamplified subminiature microphones for audio monitoring * user-selectable microphone sensitivity on 4 differen levels * totally wire-free construction (no dangling antenna cables) * double operating mode (passive: audio monitoring is possible upon direct cellphone call; active: audio monitoring is allowed upon voice detection only by automatic outgoing call from the equipment) .