hi to all, I have purchased from ebay from Gpsforless universal travel charger. it is very useful to carry it in you bag when you are not at the desk for iPhone. I have a battery pack for my iphone but when I am using it with gps for iPhone battery finishes sooooo faaast. so I needed a charger with replaceable battery. it is this charger. battery is very general and cheap Nokia battery. ehich you can find theoretically every phone shop. plus I can use it for charging for my small Nokia phone :). a must buy item for iphone users.