Info from Penon's website
4 Dynamic Driver Audiophile IEM
The QUATTRO uses an independent 3-way crossover and 3-independent conduit design for better layering performance.
The low frequency uses the latest horizontally opposed dual low frequency driver to further enhance the bass effect.
Middle frequency uses new generation of graphene materials, more rich details and listening.
The high-frequency uses new process makes the sound smoother and more delicate.
1 x 6mm custom dynamic driver for High frequency
1 x 8mm graphene diaphragm for Medium frequency
2 x 10mm composite diaphragm for Low frequency
Impedance: 16 Ohm
Sensitivity: 100dB
Frequency response: 5-30kHz