This two-way GSM audio device alerts you when it detects sounds in the surrounding environment. To use, simply insert a GSM SIM card and program it to call your phone number. You can place multiple devices in various locations such as the bedroom, living room, conference room, or office. Insert a SIM card into the device, and it is ready for use.This two-way audio device offers two functions: (1) Call the device and instantly listen in on surrounding conversations. The built-in microphone has a range of up to 7 meters, allowing clear audio pickup. (2) The device automatically calls you when it detects sound, offering responsive monitoring capabilities.Key features: Audio device, Auto Dialing function, Quad-band GSM compatibility Product Notes: - When sound is detected, the device will call your cell phone - Recharge the device using the included USB charging cable - This product is intended for lawful use by law enforcement or licensed professionals for investigative purposes Specifications: - Primary Function: Quad-band GSM Two-Way Audio Device - Materials: Plastic - Color: As shown - GSM Frequency Compatibility: Quad-band (850MHz, 900MHz, 1800MHz, 1900MHz) - Microphone Range: 57 meter radius - Power: Built-in 400 mAh Rechargeable Battery - With continuous operation, expected working time is 58 hours - In standby mode, battery life lasts 1621 hours - Dimensions: 4.3 x 3.2 x 1.4 cm Package Contents: 1 x Audio Device 1 x Charging Cable Note: Light reflection and different display settings may cause slight color variations between the image and the actual item. Measurement may vary by +/- 13 cm.