I've used all these brands and although the mechanisms always worked, the batteries all went to shit in less than a year. I put the usual homeowner type use to them, use them non-stop the first two weeks, then they sit. Sit on the charger, sit off the charger. When I need them again the batteries won't hold much of a charge. All except the Bosch. The early, early 9v used Bosch drill out lived a new Dewalt with much bigger battery. The new Bosch units will out work me in a day. Got a 1/2" hammer drill and 1/4" hex impact for $200. Incredible power.