Mandrels, collets, and chucks connect bits and attachments to rotary tools. Mandrels are shafts with a shank that attaches to a rotary tool and a head that accepts a compatible attachment. They are commonly used to hold cutting wheels and sanding bands. Collets are sleeves that fit inside a rotary tool's spindle to grip the shank of a bit or attachment to center it in the spindle and prevent it from wobbling. They are held in place by a collet nut and can be interchanged so that the collet opening matches the shank diameter of the bit or attachment. Chucks are clamps that thread onto a rotary tool spindle and have internal jaws that adjust to grip a range of shank diameters. Also called multi-chucks, they are an alternative to a collet and collet nut.