Lightweight and secure enough for vigorous active use, the MDR-J10 headphones--part of Sony"s hear line--feature a comfortable, vertical, in-ear form, a clip-on fit that follows the contour of your ears, and a stable, non-slip design built to withstand exercising, skating, dancing, or other sports. The MDR-J10 ear cups use an open-air design that lets you hear ambient sound. This ability to hear outside noises is a safety issues as much as a quality of sound issue. With these headphones, you can keep track of car horns, passing bicyclists and barking dogs.