On Ear Headphones. Koss Porta Pro KTC, the most sophisticated version of the Porta Pro, features a new technological upgrade which brings listeners closer to the music they love. Koss Touch Control (KTC) remote and microphone technology, made for iPhone, iPad and iPod, gives listeners more control in fewer steps. Listeners are now able to stay connected, shuffle song and adjust volume with the flick of a switch. Koss Porta Pro KTC features the standard setting sound performance the original Porta Pro established over 25 years ago. Designed for those with refined musical taste, the lightweight Koss Porta Pro KTC does not sacrifice practical functionality for great sound. Constructed from Mylar, the elements are extremely rigid, minimizing mechanical distortion and ensuring exceedingly accurate sound reproduction. Koss Porta Pro KTC feature dynamic elements that deliver exceptionally rich, deep bass, more control and a remarkably wide frequency response to capture every nuance in your favorite movie or musical performance. Specifications: Frequency range: 15-25,000 Hz, Impedance: 60 ohms, Sensitivity: 101dB SPL/1mW, Cable: Straight, Dual Entry, 4ft. Finish: Black