This product is a life saver. For those times when the smartphone just will not last an entire day, this product helps me out.  I like how the cable that chargers your phone also serves as the cable that chargers this spare battery.  That is a nice touch that keeps me from having to carry too many cords.  This device is about the same size as a smartphone but has the thickness of a deck of cards. I find though that I can easily put this battery and my smartphone easily into my coat or suit jacket pocket without issue to allow the phone to charge.  The indicator lights on the battery seem accurate, both to display the charging status of the spare batter itself and the discharge rate when it is charging my phone. My only wish for this product is that it would supply 1A instead of 600mA, in order to charge the smartphone faster.  Overall, this is a great product.