Unveiled at the 2012 CES to a receptive audience of battery-drained iPhone 4/4S users, Incipio's new OffGrid Pro ($100) isn't the first case we've seen with the ability to swap rechargeable cells, but it's definitely a very polished implementation -- worthy of our 2012 Best of Show Award. Based upon the original OffGrid design, OffGrid Pro amazingly packs an even more powerful 1700mAh battery inside, housed in a thin rectangular block that can easily be removed and swapped with an included 1700mAh spare. Unlike rivals, Incipio includes not only the case as a battery charger, but also a standalone battery charger that can refuel the second cell while the first is being used; the pieces are so compact that both batteries and the charger can fit inside the frame, a major space savings relative to typical iPhone batteries. OffGrid Pro is amazingly thin given its capacity, adding only a modest bump to the iPhone's flat back, while providing button coverage and all the openings you'd expect. Only the headphone port hole is a challenge: it's as small as Apple's latest plugs, and therefore incompatible with many headphone brands unless you use an adapter.