Since the primary victim of the phone thinness wars has been battery capacity (and because no-one seems to value user-replaceable batteries anymore), carrying around a backup battery has become the easiest way to make sure your phone stays ready to use all day. Adata's latest power bank, the D8000L, provides up to 8000 mAh for folks with no time to search for an outlet mid-day.
Power banks usually have a bunch of extra functions of questionable utility, but Adata actually had a good idea with the D8000L's integrated flashlight. The LED-based light occupies the entirety of one side of the power bank. The company says it can produce up to 200 lumens of light for 17 hours straight. The back of the power bank is rubberized and grooved to let owners prop it up easily so that it can shine directly on any task at hand.
The main purpose of a power bank is still to be a big battery, though. The D8000L has two USB Type-A ports that can provide a total of 2.1 A of current, and its 8000-mAh capacity is around double that of most smartphone batteries. Adata says the device is dust- and water-resistant enough to earn an IP54 dust and water-proof certification, and that it packs a panoplia of protection circuitry to prevent over-charging, over-discharge, overheating, and other electrical maladies.