Mini Syllable D50 Wireless Cordless Bluetooth Headphone Earphone Headset with Mic for Drivers (Black) 1. Driver: 8*4 mm environment friendly Black magnetic design, low frequency is more powerful. 2. Impedance16 OHM 3. Bluetooth VersionBluetooth V3.0+HS 4. Power levelCLASS II 5. Output power30mW THD+N=1