Update 6/29/15: The PMX 680 earbuds have been discontinued by Sennheiser, but is still available on Amazon in limited supply. One of the most popular sports headphones in the headphone series created by Sennheiser and Adidas is the PMX 680 Sports Earbuds. Pros Ergonomic Neckband.  A lot of runners swear by using a neckband to […]