Flexible and clever: In these comfortable models, Sennheiser has replaced the conventional headband with a flexible, thin plastic tube with a metal core. This unusual, patent-pending design ensures that the earphones “coil up” after use and elegantly slide into the included case. The flexi-headphones weigh in at only 10 g and adapt to the shape of the wearer’s head, ensuring a perfect fit for sports. While the LX 70 is a model of the “Sport” range and comes in fresh green, white and sporty light gray, the LX 90 is part of the elegant “Style” line, combining classic black with metal parts.