The technical specifications had been changed for the new Westone 3 according to the Westone official website: http://www.westone.com/content/264.html
And the previous technical specs were:
Sensitivity – 119 dB/mW
Impedance – 27ohms
Drivers – 3 balanced armatures with 3-way passive crossover
EDIT: So these will have about the same sensitivity as a ER4p right?
Sensitivity: 107 dB SPL
Frequency response: 20 Hz -18 kHz
Impedance: 30 ohms
Driver: Balanced armature
Features: Soft padded travel case, ten different eartips, and wax loop for cleaning.
Standard Color: Black