I am looking for a pocket-sized external battery to work with a handheld DVR. The manufacturer does make an external battery pack, however the manufacturer of the device is located in Korea, and no US dealers sell it. From the product manual, it states that the manufacturer's external battery pack runs on... 3pcs of Alkaline UM-2(R14/1.5V) (Regular "C" batteries I think.) The manufacturer's battery pack hooks in to the unit's AC/DC adaptor outlet. The specs are DC5V 2A. The unit has an included internal battery, which a is 3.7[V], 2000[mAH] lithium ion battery. Can you think of any pocket sized solutions to my problem here? What do I need to look for in a battery pack that would work? Thanks very much.