The iBasso Audio SR3 is an open, over-the-ear headphone with a replaceable Jack cable and bio-cellulose technology diaphragm, dynamic driver and Tesla magnet. With 150 Ohm impedance, the SR3 offers more detailed highs, more refined vocals and a pleasantly more powerful bass than its predecessor. The package also includes an excellent 4.4mm symmetrical cable and a 6.35mm converter. Highly recommended for lovers of electron tube sound!