Flexible flipbook, two-way design allows you to wear the headphones either in-ear or behind-the-ear Product Note : If the size of the earbud tips does not match the size of your ear canals or the headset is not worn properly in your ears, you may not obtain the correct sound qualities or call performance. Change the earbud tips to ones that fit more snugly in your ears Thanks to twistable and flex soft technologies, these headphones are lightweight and ergonomically built to ensure secure fi t and stability no matter the workout. Sweat proof In-line one button remote with microphone enables hands-free calling Magnetic earbuds that allow for easy cable management when not in use Compatible devices: Smartphone Dynamic frequency response range (Hz) - 20Hz – 20kHz