Koss UR29 Collapsible Portable Headphones High fidelity stereo phone utilizes an anisotropic magnet and 1.4 mil Mylar element for deep bass and treble clarity Frequency Response: 18-20,000 Hz Collapsible design for protective storage and maximum portability when listening on the go High fidelity stereophone utilizes an anisotropic magnet and 1.4 mil mylar element for deep bass and treble clarity Frequency Response: 18-20,000 Hz Collapsible design for protective storage and maximum portability when listening on the go