30 Hours Continuous Music Playback Time: Whether it is long hours at the office or intercontinental travel, with the TT-BH040 has your back with up to 30 Hours of playing time per charge. 2 Large-Aperture Drivers: The 40mm drivers of the headphones produce a balanced, powerful sound that will give your music the best possible playback. Built-in Mic & Clear Calls: Take calls without taking out your phone out of the pocket. Crisp and clear connection both ways through the headphones’ built-in microphone