Incredibly, incredibly strong, despite being so small. Before I bought this marvel I had worn with a rim cross and WD40 for a couple of hours on a fixed rusted wheel bolt. Finally I gave up, bought this DCF880, threw on a 2 Ah battery I had earlier and five seconds later the nut was loose. Hardly thought it was true. Now I also have an adapter so that the machine can be used as a regular screwdriver for house renovations. It allows me to have a drill bit on my old DeWalt drill screwdriver, and torx bits on this one.