The newly designed AKG® K551 headphones are optimized for a fully immersive listening experience and for comfort. Starting with a 2-inch (50-millimeter) driver on each ear, these reference-class headsets use Real Image Engineering to create a highly realistic sound environment with a true sense of dimensional space. Lightweight, with a comfortable fit, AKG K551 headphones have incredible passive noise reduction and extremely low sound-leakage levels that will keep you living blissfully inside your sound environment for hours on end. 2" (50MM) Driver A powerful, 2-inch (50-millimeter) driver enables the AKG K551 reference-class headset to do things that other headphones can only dream of. Music is rich and layered, while audio environments seemingly unfold before your eyes, with sound that's undistorted no matter how high you turn up the volume. Real Image Engineering Imagine the amount of space between your ears and your AKG K551 headphones. Now imagine the amount of space in an actual soundstage. Real Image Engineering is the science that fits the big space inside the little one. With Real Image Engineering, sounds are huge and accurate, with an incredibly realistic sense of width, distance and depth. Low Sound-Leakage Levels You love your music. The person sitting next to you doesn't. Not a problem. AKG engineers have optimized the K551 headphones for minimal sound leakage so that your music is yours and yours alone to enjoy anywhere you go.