In-Ear Detachable Earbuds. Features: The F9 utilizes a hybrid design in which each channel is composed of one dynamic and two balanced armature (BA) drivers. The 9.2 mm dynamic driver is specifically tuned to produce bottomless lows while the two BA drivers precisely portray extended upper-mids and highs. The F9 utilizes the standard MMCX connector for its interchangeable cables, and comes standard with both 2.5 mm balanced and 3.5 mm single-ended cables. For instance, the F9 comes with two different kinds of ear tips – one set optimized for bass while the other is designed for a more balanced presentation. Each type of ear tips comes in small, medium, and large sizes. The F9 also comes with our popular waterproof carrying case. Specs: Frequency Response: 15 Hz ~ 40 kHz. Sensitivity: 106 dB/mW. Impedance: 28 Ω. Weight: about 21 g. Colour: Black.