KG engineers have optimized the AKG K551 headphones for a fully immersive listening experience. Starting with a 1-31/32-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 three-dimensional space. Stylish and portable, the AKG K551 lets you take AKG studio-quality sound with you go wherever you go. And an in-line microphone lets you take calls from your iPhone. The lightweight, comfortable AKG K551 also has impressive passive noise reduction and extremely low sound-leakage levels. So you can stay blissfully inside your sound environment for hours on end.