On a recent trip the IMP500 recharged my cell phone and operated and recharged my Nook color reader twice without needing recharging itself.  The Nook color reader has about an 8 hour battery life on its own. Using the IMP500 I was able to continue reading past 12 hours, plus it was 3/4 charged when I disconnected the NOOK. The IMP500 perfomed as advertised. It's easy to use and light to carry. When using the NOOK reader, I just dropped the IMP500 in my shirt pocket connected to the reader by the NOOK USB cable. I highly reccommend acquiring a short pocket if you do not already have one. Recharging is fairly quick with any of the standard usb chargers (the one it comes with, the NOOK charger, or an Apple IPhone charger).  This is good, since it measns carrying only one charger.  This is a simple device that solves a major problem of not havng enough battery life in the devices you carry. It also charged my iTouch-4 with no problem on th esame trip.