This two-way GSM audio device alerts you when it detects sound in its surroundings. Simply insert a GSM SIM card and program it to your preferred phone number for notifications. You can deploy multiple units in various locations such as bedrooms, living rooms, conference rooms, or offices. Once a SIM card is inserted, the device is ready for use. The device offers two key functions: 1) Call the device from your phone to remotely listen to surrounding audio. The built-in microphone captures sound within a 5–7 meter radius. 2) The device automatically calls you when it detects sound, providing real-time alerts. This functionality enhances its performance compared to standard GSM audio devices. Key features: Hidden audio gadget, auto-dialing capability, tri-band GSM support. Product notes: The device will call your phone when sound is detected. It can be recharged using the included USB charging cable. This product is designed for use as an investigative tool by law enforcement or licensed professionals. Specifications: - Primary Function: Tri-band GSM two-way audio device - Materials: Plastic - Color: As shown - GSM Frequency Compatibility: Tri-band (850MHz, 900MHz, 1800MHz, 1900MHz) - Microphone Range: 5–7 meter radius - Power: Built-in 400 mAh rechargeable Li-ion battery - With control function enabled, continuous working time: 5–8 days - Standby time with positioning function: 16–21 days - Dimensions: 4.3 x 3.2 x 1.4 cm Package Contents: 1 x Locator 1 x Charging cable Note: Light reflection and display differences may cause slight color variations between the image and the actual item. Measurement error allowance: +/- 1–3 cm.