Designed for High Impedance and Low Sensitivity Headphones – Easy to Carry and Use In The Outdoors – Increases Your Headphone’s Bass & Sound – New Amplifier IC with Higher S/N and Lower Distortion – Portable Headphone Amp for iPod, MP3 Player, Laptop or Mobile Phone – Boost Volume and Reduce Battery Drain of Portable Players – Built-In Rechargeable Battery (Charged Via USB) – Robust Metal Casing For Everyday Use – Ultra Low Signal to Noise and Distortion Specification