The estick is a compact mobile power supply specially designed to be used with the fiio ka17 and qx13. It perfectly pairs with the ka17 qx13 and provides an independent supply of power to it, avoiding consuming the battery of the phone device connected to the ka17 qx13. Pure power ndash pure sound the power output circuit is equipped with low esr tantalum capacitors to ensure a stable and pure power supply with less power ripple ndash leading to a purer and more detailed sound. Compact statue ndash enormous battery life the estick can provide the fiio ka17 or qx13 with up to 5 hours of battery life. The intuitive power indicator light ensures you can easily grasp the esticks status and simply allows you to enjoy uninterrupted high quality music. The listing is for the estick only, no amplifier included