Mount these chucks to the slot-drive, straight-shank spindles on older drills and mud mixers. Their slot-drive design locks these chucks onto your tool, so they won’t slip on the spindle, no matter how often you start, stop, or reverse. They hold bits just as tightly—use the included key to tighten or loosen the jaws. These medium-duty chucks are strong enough for drilling through hard materials and mixing thick liquids and slurries. For a long life and improved accuracy, they have a one-piece sleeve, center-ground jaws, and hardened wear points. They’re also known as positive-drive drill chucks.