Custom Art's 6 Balanced Armature IEM. Driver configuration: Dual sub-low, Single low, Single mid-high, and Dual super-high drivers Sensitivity: 113dB @ 1kHz @ 0.1V Impedance: 6.6 Ohm @ 1kHz (+-0.75 Ohm 10Hz-20kHz) Frequency range: 10Hz-18,000Hz (+-20dB into IEC 60318-4 coupler)