Aiming for the sound of a custom in-ear monitor with the convenience of a universal fit, the Ultimate Ears UE900s is well suited for personal listening and professional applications alike. The IEM features a small shell that rests comfortably in most ears, regardless of size or shape, thanks to the proprietary fit tip system. With nine different tip sizes to choose from, you can simply lift up the tip sticks and find the best fit. The tips sit on the tip sticks in a unique angle to create an excellent seal. This IEM has four proprietary balanced armature drivers: two for bass, one for midrange, and one for treble. The quad design delivers rich, clear audio, while the three-way crossover and dual bore sound channels keep the highs, mids, and lows phase aligned. Finally, the removable MMCX cable is equipped with an inline mic and iOS controls.