Features: 1.Miniature Earpiece: Headset with a miniature wireless induction receiver that converts audio signals through electromagnetic induction for covert communication when it is inconvenient to expose the headset. 2.Automatic Connection: Compact and portable GSM module automatically connects the call and then transmits the call sound to the headset in real time. 3.Stable Signal: The headset uses a cell phone signal, so you can talk anywhere there is a cell phone signal, stable signal and performance. 4.Features: Wireless headphones have small size and loud sound, comfortable to wear without overburdening your ears. 5.Clear Voice: Small earphone is widely used in many departments, using this device, you can clearly hear each other's voices. Specification: Item Type: GSM Wireless Earpiece Material: ABS Product: Approx: 12mmx7mm/0.47x0.27in Applicable Battery: 337 (SR416SW) 15mAh button battery x1 (with supporting battery x2) Total Working Hours: 6 hours Distance from A808 earpiece to GSM Module: Approx: 40cm/15.74in GSM Module Parameters: Product: Approx: 5x3.5x13cm/1.96x1.37x5.11in Polymer Battery: 650mah Lithium Battery x1 (built in) Band: GSM 2G full band PackageList: 1 x GSM Module 1 x Earphone 2 x Battery 1 x Earphone Storage Box 1 x Storage Box Note: 1. Please allow slight error due to manual measurement. Thanks for your understanding. 2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard.