The best In-ear Wireless Sport Headphone features that makes it the leader in sports headphones, with more models available than any other manufacturer. This is a great headphone for working out at the gym, with exclusive monster secure fit that lets you move freely, yet still stays put. High noise isolation lets you focus, and Achieve is completely sweat-proof so you can work hard and listen loud with monster performance sound. Five-plus hours of battery life mean you can go longer than you thought possible.