Turn up the heat and let nothing get in your way! The Sennheiser/adidas PMX 680 neckband headphones are not only lightweight and sturdy, they also stay extremely secure in your ear while you run or work out in the gym. Sound-wise, their high-output drivers deliver a powerful and energizing stereo sound. These headphones have been designed and tested for heavy movement. Their strain relief parts are made of highly-flexible, shock-absorbing material while the cable is D…