Product Description:(1) Make a call to the audio device and you can instantly listen in to conversations! The built-in microphone works up to a 7 meter radius、 so set this bug up wherever you want!(2) 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.Hot spots:Hidden Audio Spy GadgetAuto Dialing optionTri-Band GSM Audio Spy DeviceSpecification:Primary Function: Tri-band GSM Two-Way Audio Spy DeviceMaterials: Molded PlasticColor: BlackGSM Frequency Compatibility: Tri-band (850MHz、900MHz、 1800MHz、 1900MHz)Microphone Range: 5-7 meter radiusPower: Built In 200 mAh Rechargeable Li-ion BatteryWorking Time: 5 hoursVoice Control On: 3-5 daysVoice Control Off: 12-15 daysDimensions: 4.3x 3.2 x 1.4(cm)Plug: EUPackage Included:1x Two-Way Audio Spy Device1x USB Cable1x Power Charger (110-220V)1x User Manual(Chinese and English)NOTE:As the effect varies from monitor to monitor、 there is irrevocable slightly difference in colors between the color showed on your monitor and the real one、 So if dear you can not accept this very little difference、 be cautious before you making the orders.thanks for understanding.