A very satisfied and proud owner of iBattz. Just a quick thought... Been on the long hunt for an absolute battery pack that will not only provide additional juice but a definite quality and practicality. Quality - well coming off the shelf, it does have a sound built, from the packaging and the actual unit, instructional guides - its light / handy even with your IP4/S all together. The texture is rubber-ish which spells comfort and right grip for added safety with daily use. Practical - with the its price tag, this is a true value for money. Coupled with 2 bumpers (red / silver) and an option of either a single battery or 2, might just be right for you depending on your intended use - casual users, professionals or to frequent travelers that requires that much juice whenever wherever. Lastly, the interchangeable / replaceable battery feature (just incase you get it used up to the point of disposing it) is just a breath of fresh air in this category as most or if not (all) has its usual built-in battery, upon wearing it off will lead to absolute disposal of the entire system - which means an investment down the drain... of course a worthy investment since it has been used and consumed. Well, just for the record, from 20% IP4/S battery (upon activation and consumption of iBattz in full charge state) - It went to 98% with a single iBatzz battery consumed. Wasn't able to get the approximate time it went to 98% charge, but it's fairly quick (not even heating up) as compared to others I've used before. I've had my share of impulsive buying on 3rd party gadget add-ons specific to extended batteries, and mind you this is something I know will best fit my need - But as they say, it does will wear off, well if that time comes I know I'll just have to simply replace the batteries and not the entire system - making it a lot more simpler. To Charlie and his crew - thanks for bringing in another innovative product. More to come! Cheers!