I bought this light to be used during emergencies, replaced the standard bulb with a Cree 13.5 LED bulb.  and purchased a 14.4 volt  DeWalt battery pack.  This is an AWESOME combination.  THe Flashlight operates for a continuous 40 hours before dying, with about 400 lumens of brightness.  We had a several day power outage as a result of a recent hurricane, and this light made all the difference.