Product details of i7s TWS Mini Wireless Bluetooth Earphone Stereo Earbud Headset With Charging Box Mic For iPhone Android All Smart Phone Drive: 15mm Impedance: 32 OHM Bluetooth version: Bluetooth v4.1+EDR Bluetooth frequency: 2.4GHz Power level: CLASS II, output power: 30mW Bluetooth Distance: obstacle free 10 meters Drive: 15mm Impedance: 32 OHM Bluetooth version: Bluetooth v4.1+EDR Bluetooth frequency: 2.4GHz Power level: CLASS II, output power: 30mW Bluetooth Distance: obstacle free 10 meters