Etymotic Research HF2 Earphones / Headset (iPhone Compatible) - Ruby

The hf2 is a high-fidelity, hands-free noise-isolating headset and earphones combination. But it's really much, much more than that. The hf2 provides a near-perfect music experience. Made by Etymotic Research, the people who created in-ear earphones, the hf2 delivers Etymotic's world-renowned sound quality in a comfortable, convenient wireless phone headset, so you'll never miss a call.
The headset includes an in-line microphone and a Music/Call button that allows you to quickly answer calls while contolling your music. You'll be able to hear and be heard, clearly, even in a noisy environment. The hf2 includes the in-ear headset and earphones, assorted eartips so you can find the ones that fit you best, carry pouch and filter changing tool with filters.
Works with iPhone and other music phones that operate with a 3.5 mm/4-contact phone + stereo plug. Compatible with most music players (e.g., iPod, mp3, CD) that accept a 3.5 mm stereo plug. hf2 headset + earphones can be worn with the cables in front or in back of the head. The cable slider can be adjusted by moving it up or down for a snug fit.

Technical Details :
* Headset and earphones for iPod, iPhone and other mobile phones.
* For music phones and music players that take 3.5 mm/4-contact phone plus stereo plug.
* Highest noise isolation of all competing headsets.
* Exceptional sound quality.
* 20Hz-16kHz frequency response accuracy, 16 Ohms impedance.



How Etymotic Research Measures Response Accuracy ?
The accuracy score is perhaps the single most important tool for earphone design. A perfect recording of a live performance played through earphones with 100% accuracy would produce the same sound at the eardrum as the live performance. A complicating factor is that the acoustic resonance and horn effects of the ear change a flat signal entering the open ear to an eardrum signal with the approximate frequency characteristic of the target curve. A perfect earphone will create that same frequency characteristic at the eardrum.

Pros :
These have by far the best sound ever experienced in headphones. They are comfortable, or at least after a couple of days to get used to the feel of them. Once properly inserted, there is a full mobility with no fears of them slipping out. One can see two bags that contained dozens of replacement covers - very nice touch.
Cons :
These are the first isolating headphones. It does cause some strange internal sounds, like if you try to eat while listening to music, the chewing noises are very loud (kind of like chewing with your fingers in your ears.) Also there is some noise that gets transmitted from the cords into the ears.