Sennheiser earphone PMX80 

The PMX 80 Sport II stands up to your toughest workouts. These rugged stereo neckband headphones feature an ergonomic neckband and vertical transducer system for an optimum fit and comfort. Their sweat and water-resistant construction also makes them an ideal companion for all music-loving sports enthusiasts. Max Spl - 121 dB (1kHz/1Vrms) Transducer Principle Dynamic THD Less Than 0.1% Weight - 16 grams