this is the only review you need to read. i have used many many headphones over the years. i have audiophile grade head phones and sports headphones. The Trekz Air are, imo, sports headphones. i use them for running, xc skiing, and at the gym. i wanted headphones where i could still here what's going on around me....important for running or XC skiing. but they are plenty loud enough and the sound quality is just fine. don't expect audiophile sound. the other feature that is excellent is the fit. many headphones don't fit my ears (Bose), so i give them away to my kids. the trekz air, imo, fit perfectly. not too snug (no headaches), but very stable for trail running or xc skiing. and no problem with sweat. the functionality is great...very few buttons and easy to access while running. and if you are skeptical about the technology, don't worry, it works great. in fact, the more i wear them the more i like NOT having something sticking in my ear...which can give me ear fatigue after an hour or so. i gave five stars for noise cancellation because these do not cancel out noise, nor are they supposed to. you can here just the right amount of noise. if you want practically no noise to creep in (airplane), they provide a set of foam ear protectors...this does the trick. although you might bug the person beside you with the faint sound that comes out of these headphones. for quieter applications, i would recommend other headphones. again, these are great for sports!