Detailed Product Description 1)Magnetically Shielded 2)Build-in Amplifier 3)Drive Unit 3 Speaker 4)RMS: 2W 5)Frequency Rang: 160-20KHz 6)Impedance 4 7)T.H.D: Under 0.5% 8)Input Sensitivity: 260 9)Power Supply: DC 2.5-6v 10)Produce Size: 110x86x24mm 11)Packing: BOX Size (40 sets/CTN) 12)Size: 410x372x252mm