The MX 685 is part of the Sennheiser/adidas series of sports headphones. Developed and designed with professional athletes, the series offers improved fit, comfort and acoustics for even the toughest workouts. The MX 685 delivers energizing, stereo sound and an in-ear design for greater situational awareness and safety. The rugged, water resistant construction features para-aramid reinforced cables, strain-relief parts and a slide-to-fit holding mechanism to ensure a perfect fit.