Feature: Super mini size, easy to carry. Very easy to use: just call the SIM number installed in the device. Within seconds, you can hear audio within a 10-meter radius. GSM Quad Band (850/900/1800/1900 MHz) ensures global compatibility. Built-in dual microphone design for clear sound quality. Supports preset phone numbers. Element type: Two-way audio device. Acoustic alert function available. Long standby time: built-in 200mAh lithium-ion battery lasts 3-5 days with acoustic alert enabled, up to 12-15 days when disabled. Materials: Molded plastic. Dimensions: 4.3 x 3.2 x 1.4 cm. Power: Built-in 200mAh lithium-ion battery. Color: Black. Voice activation duration: 3-5 days (on), 12-15 days (off). Main function: Tri-Band GSM two-way audio monitoring device. Working time: 5 hours. Microphone range: 5-7 meters radius. Package includes: 1x bidirectional audio device, 1x USB cable, 1x user guide (English). Note: Color may vary slightly due to different screen settings. Our products are made with high-quality materials and designed for optimal performance. We aim to ship all orders within three business days. Estimated delivery time is 8-15 days. Please review product dimensions carefully before purchase. Detailed product information is provided in the title and specifications. Customer satisfaction is our priorityfeel free to with any questions. Thank you for choosing our product.