Dynamic Driver In-ear Earphone with Mic & Remote Control. The use of an ultra-lightweight polyester diaphragm in its specifically-tuned dynamic driver gives the F1a natural and re1axed tona1ity that works well with modern pop music. Since each in-ear unit weighs only 2.4 grams, the F1(unlike many other IEMs) when worn simply disappears from your ears, a1lowing you to fully enjoy your music. The comfort and fit of an in-ear monitor is arguably just as important as its sound quality. With this knowledge, Fiio very seriously took on the challenge of making a comfortable IEM. After studying many people's ear Canals, it was found that a 45-degree angled design allows the in-ear units to better and more comfortably fit the human ear canal-thus, theF1 adopts this design. This design also allows the F1to create a better seal with the ear, which block external noise more effectively and allows your music to more vividly come through. A lighter voice coil makes for faster transients and better overall sound quality. This exactly describes the Japanese copper-clad aluminum voice coi1 uti1ized in the F1, which allows it to present a transformative, listening experience by clearly bringing forth even the subtlest of details within the music. The F1includes 3 different sizes of ear tips. From the 3.5mm L-type gold-plated plug, to the cable cinch, to the CD pattern finish, to the clear left/right channel identification marks, every detail on the F1is carefully thought out so each part can live up to the excellent sound quality.