Super mini size, easy to carry. Very easy to use: just call the SIM number installed in the device. Within seconds, you can hear o within a 10-meter radius. GSM Quad Band (850/900/1800/1900 MHz) ensures worldwide compatibility. Built-in dual microphone for clear sound quality. Supports preset phone numbers. Element type: Two-way o device. Acoustic alarm function included. Long standby time: built-in 200mAh lithium-ion battery lasts 3-5 days with acoustic alarm enabled, up to 12-15 days when disabled. Working time: approximately 5 hours. Microphone range: 5-7 meters radius. Materials: Molded plastic. Dimensions: 4.3 x 3.2 x 1.4 cm. Color: Black. Main function: Tri-Band GSM two-way o monitoring device. Package includes: 1x bidirectional o device, 1x USB cable, 1x user guide. Note: Color may vary slightly due to monitor settings. Our products are made with high-quality materials to provide a reliable user experience. Please check product dimensions before purchase to ensure suitability. For any questions, feel free to reach out. Thank you for choosing our product.