Koss KEB70 Aluminum Isolation Earbud (Silver) (Discontinued by Manufacturer) High quality aluminum isolation earbud - accurate sound reproduction, comfortable design Includes small, medium and large silicone ear cushions for a customized fit to enhance isolation Convenient carrying case for protective storage included. Frequency Response of 15-20,000 Hz. 4 ft straight cord, dual entry 3.5 mm plug.