I would like to say I purchased the imp 500p back in November and found the product very useful with my iphone 3GS with my  usage of the phone the stock battery last a couple of hours with this unit I get a full day of fun with my phone plus some also I had a charging problem with the unit 4 months of the purchase and New Trent stood by there product and replaced the unit with no hassle all I can say is this company has an excellent product and they stand by it. Thanks again New Trent