Headphone experts have long recognized the sonic benefits of an open back design while closed back headphones are often a necessity when traveling or listening in close quarters such as an airplane. HIFIMAN gives you the best of both worlds with an on-ear headphone that can go from one mode to simply by adding (or removing) the logo cap on the ear cup. Engineers have cleverly optimized the performance in each mode to make this not only possible but also quick and easy. Performance: At the heart of the Edition S is a 50mm dynamic driver designed for full range frequency response with exceptional detail and imaging. With a sensitivity rating of 113 dB and impedance of 18 ohms, the HIFIMAN on-ear headphone can be driven by most portable audio devices such as smartphones and iPods. Completing the connection, Edition S is fitted with a high performance Oxygen Free Copper cable that is 1.3 m long and terminated in a 3.5mm mini jack. For added convenience, this iOS/Android cable is equipped with an in-line control and a microphone. Comfort and Convenience: Edition S folds in a compact shape for easy carrying and comes supplied with a travel case. Weighing in at only 8.74 ounces (248 grams), S can be worn comfortably for hours on end thanks to its light weight and padded headband. The ear cups and pads generally follow the shape of the human ear offering further comfort to the listener. A 6.35mm (1/4") phone jack adapter is supplied allowing the owner to plug Edition S into portable or HiFi equipment.