The battery inside the iPhone 3G has a 1150 mAh capacity. 3G JUICE DeLuxe boosts your phone with 1800 mAh, stronger then the normal battery.
So whenever the battery icon on your iPhone 3G is coloring red, plug in 3G JUICE and keep surfing. The high capacity, compact size emergency battery is small (62×60x12.9 mm) and gives your iPhone 3G a steady 5V.
BONUS: it works also with most iPods.