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! Headset includes a high-sensitivity 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.