The Westone B30 features a full-range, three balanced-armature driver with 117 dB SPL @ 1mW sensitivity, 15Hz – 18kHz frequency response, and an impedance of 110 ohms @ 1kHz, 25dB passive noise attenuation
The Westone W20 features a full-range, dual balanced-armature driver with 117 dB SPL @ 1mW sensitivity, 20Hz – 18kHz frequency response, and an impedance of 33 ohms @ 1kHz, 25dB Passive Noise Attenuation