My new IMP52D is great.  I opened the package 5 days ago and read the directions that told me that the battery is also a flash light.  Two minutes later the lights went out do to an electrical storm. I was so glad to have such a helpful item.  The next day my phone battery started to decline significantly.  Once the iPhone 4S battery goes down to 20 % battery the battery drops very fast. The new small battery charger saved the day and not only stopped the decline but put the charge back up to 100% in a very short period of time.  I am a nurse practitioner and need my phone for many medical functions.  I highly recommend this small battery charger.