Built-in Magnet Switch, Headset can be automatically ON/OFF when the Magnet separate /attract, intelligent prediction of your requirement, no need any key operation, enjoy your music in the next second. Built-in magnets let you attach the two headphones together when not using, and wear like a necklace around your neck, a convenient way to carry. Bluetooth 4.1 pairing with smartphones instantly. Bluetooth signal has 10m stable transmission distance. Supports two connected devices simultaneously and automatically connects after being paired successfully for the first time. This cordless earphones are universally compatible with iphone, ipad and android smartphones. Specifications: Brand: Awei Model: AK3 Bluetooth Version: CSR4.1 Battery Capacity: 130mAh Sound System: Stereo Dual Track Battery: Rechargeable Lithium Polymer Battery Support Profiles: Headset, Handsfree IOS Battery Displays: Yes Talk time: 12hours Music time: 10hours Charging time: 2hours Volume Control/Next song: Yes Voice Prompt: Yes Support: HSP/HFP/A2DP/AVRCP/CVC Input charging Standard: DC 5V Sensitivity: 92db ± 3db Resistance: 16Ω ±15% Frequency response: 20-20000 Hz Best Transmission Distance: 10m(barrier-free space) Feature: Support connect two device at the same time Package Includes:: 1x Awei Ak3 Bluetooth Earphones 1x USB Charging Cable 1x User Manual