GOgroove Bluetooth Running Headphones with IPX4 Sweatproof Sports Technology , 8 Hour Battery , Wireless Folding Design and Mic for iPhone / Android The GOgroove BlueVIBE FXT Bluetooth Fitness Headset features a long-lasting battery providing up to 8 hours of audio playback Complete with onboard controls for volume and track , built-in microphone for hands-free calls and 3.5mm audio input Expanding headband for adjustable fit and folding design for easy storage. Headband sizing: 18 - 20 inches The IPX4 water-resistant design is ideal for sports, running and other outdoor activities. High Quality - Backed by a 3 Year Manufacturer's Warranty! TECH SPECS - Operating distance: 30 feet, Charging time: 2 hours, Audio playback: 8 hours, Input: 5V? 0.5A, Driver: 40mm, Impedance: 18 Ohms, Sensitivity: 106  4dB, Frequency response: 20Hz-20KHz