In-Ear Detachable Earbuds. Features: The F9 PRO 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 PRO 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 PRO 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. Also included with the F9 PRO are three pairs of foam eartips, all in the same one-fits-all size. The F9 PRO also comes with our popular waterproof carrying case, as well as a water-resistant neoprene carrying pouch. Specs: Frequency Response: 15 Hz ~ 40 kHz. Sensitivity: 106 dB/mW. Impedance: 28 Ω. Weight: about 21 g. Colour: Titanium.