Among the sea of USB battery packs at CES, we’re seeing an emerging trend: the ability to track remaining charge, granularly. Instead of relying on a four or five bars, they actually show the percentage in one of a few different ways. Powerocks is one of the companies jumping on this, with Smart Power 5200mAh ($80).

With 2.1-Amp output, the battery can charge most iPads and all iPhones at full-speed. The most distinctive feature is the accompanying app, which will show exactly how much charge is remaining in the battery pack, on the screen of your phone.