This two-way audio spy device comes with two amazing functions: When you Make a call to the audio device and you can instantly listen in to conversations! The built-in microphone works up to a seven meter radius, so set this bug up wherever you want! It’s Allows the spy audio device to call you when it hears people talking! This feature makes it much more advanced than other GSM audio bugs on the market today. It’s Microphone Range is 5-7 meter radius.It has Built In power of 200 mAh Rechargeable Li-ion Battery. Its Working Time is five hours with standby time of Voice Control On three to five days.