FiiO FH3 Triple Drive(1 Dynamic + 2 Knowles BA) in-Ear HiFi Earphones with High Resolution,Bass Sound, High Fidelity for Smartphones/PC/Tablet :The 10mm beryllium-plated diaphragm dynamic driver in the FH3 earphones was specifically chosen for its superior acoustic properties. The beryllium-plated diaphragm is not only light and thin but is also extremely rigid, allowing for thunderous yet lightning quick, responsive and dynamic bass. The FH3 headphones which is two Knowles drivers paired with a beryllium-plated dynamic driver ,placed near the opening of the sound tube, controlled by a physical + electronic frequency crossover system masterfully cover the entire frequency response range. High-frequencies: the Knowles RAD-33518 driver provides extremely clear sound with well-extended yet smooth treble. Mid-frequencies: the ED-30262 gives sweeter and fuller vocals as well as a wider soundstage.