Koss SB40 Computer Headset with Microphone Koss stereophone with dynamic microphone for hands-free communication from your personal computer 20 to 20,000 Hz frequency response; closed-ear leatherette cushions offer maximum isolation of sounds within and without Dynamic microphone for optimized pick up pattern (rejects off-axis sound) Adjustable, cloth sling and headband provide comfort during extended use Straight, dual-ear, 9-foot cord