TRN STM In ear monitor comes with a 10mm dual magnet dynamic driver for deep bass, paired with a customized 30019 balanced armature driver for mid and high frequencies, resulting in clear treble, deep bass and rich mid-tones and crisp vocals. Professionally tuned by TRN engineers using customized drivers, STM presents a vibrant yet comfortable sound that is non-fatiguing thus suitable for long listening. It will ascend your listening experience to the next level.