The New Trent iTorch is the smallest and lightest 5200mah external battery pack you will find anywhere.  It feels sturdy and solidly built.  This is a must have for anyone who finds themselves needing to charge their phone all the time.  I hate walking out the door with 40% left of battery life on my iPhone5 and having to not use my phone like I would like to in order to save battery.  Now I can use my phone when and where I want without worrying about the battery dying.