This device is customized to fit the exact shape of your ear canal for the best isolation and allowing no loss of bass frequencies, detail or clarity. Its all-day comfort is perfect for an activity lifestyle, even for professional athletes.THE ULTIMATE MUSIC PLAYERHigh durability aluminum shell with clip, its convenient for you to carry.Along with waterproof earphone comes four soft silicone ear cushions.Built-in rechargeable li-battery, it can work up to 8 hours when fully charged.Compliant with international IPX8 water resistance standards.DESIGNED FOR SWIMMINGWater Proof Device for the ultimate cardio activity, It takes more physical effort to swim 2 miles than to run 2 miles, swimming is a low impact exercise and easy on the joints and good for muscle recovery. With this device you wont even feel the amount of time you swim with your favourite podcast on or if its quick sprint laps, the intensity of your workout fuelled by your favourite tunes.