This is a Z011 Mini 3-Jaw Self-Centering Lathe Chuck, a compact tool designed for securing workpieces on mini metal or woodworking lathes. Made from a durable, corrosion-resistant zinc alloy, it features three jaws that move simultaneously to ensure precise centering of your project. The set typically includes the main chuck, a threaded connecting rod for mounting to a spindle or drill, and two Tommy bars for manual tightening, making it an essential accessory for small-scale precision machining and hobbyist crafts.