1) Type:necklace 2) Perform: highly accurate sound-reproduction, crystal clear sound 3) Shell Material: metal 4) Driver unit: 16mm.6u 5) Impedance: 32 6) Sensitivity: 105dB/mW 7) Rated power: 3mW 8) Frequency response: 20Hz-20kHz 9) Jack: stereo 3.5mm 10) Normal Packaging: PP bag and PE bag 11) Excellent packaging: gift box