All portable players lack the power needed to fully drive earspeakers for a clean distortion-free sound, no matter what kind they are. This little unit dramatically enhances the field of sound in your player without adding a hiss or buzz. A second headphone jack also allows you to share your music without sacrificing clarity or volume. Hear your audio the way it was meant to be heard. 4.5"×1.5"×1", 1.5 oz. runs for 22 hrs on two AAAA batteries, which are included.