DeWalt DCF850 Atomic Impact Driver vs DEWALT 20V MAX Brushless Hammer Drill DCD999B

These are different tools, not two versions of one. The DCF850 is a compact 1/4 in. hex impact driver built for driving screws and small fasteners in tight spaces; the DCD999B is a 1/2 in. hammer drill/driver built for drilling holes in wood, metal and masonry. Buy the DCF850 if your work is mostly fastening; buy the DCD999B if you need one tool that drills and drives. Owners praise the DCF850's short 101 mm body and light weight, and the DCD999B's three speeds, 11-position clutch and hammer mode.

• Choose the DCF850 if you mostly drive screws and need a short, light tool that fits into cabinets, framing gaps and overhead work.
• Choose the DCD999B if you need to drill holes in wood, metal or masonry as well as drive screws, and want a clutch and hammer mode.