You walk happily listening to the music you love. You are enveloped in the artist's world wherever and whenever you like. But, don't you sometimes wish the quality of the sound was better? The Denon AH-C551 are inner ear headphones that faithfully reproduce the original sound with a quality that is always satisfying. These headphones feature an acoustic optimizer structure that ensures ideal sound characteristics, and the canal-type design fits snuggly into your ears.