This self centering, 3 jaw micro chuck is ideal for holding small projects from the inside or outside. The provided step jaws reverse for extra versatility when securing the work piece from the outside, or inside. The smaller diameter offers a safety feature keeping your knuckles away from the jaws when working close to the chuck. Pre cut with a 1" X 8 tpi standard thread mount, and includes an adapter for 3/4" x 16 tpi spindles. Weighs only 1.2 pounds. Holds a workpiece from 3/4" to 2-1/2" inside diameter, and a workpiece from zero to 1-1/4" outside diameter. Uses small levers to open and tighten the three jaws.