Attention, precision handloaders! This is a Hornady Match Grade interchangeable bushing for use with their match-grade full-length or neck sizing dies (the die body is sold separately). The bushing size is 0.291 inches in inside diameter, and it's what actually contacts and sizes the neck of your rifle brass. The beauty of the bushing system is that you can customize the amount of neck tension by choosing different bushing sizes (available in .002\ increments). This specific .291 bushing might be suited for certain cartridges like some .30 caliber variants – always measure your fired case neck and subtract .001\-.003\ to find your ideal starting size. It's made from polished steel, is self-centering in the die, and allows for minimal brass work for longer case life and better accuracy. If you're into serious precision rifle reloading and use Hornady match dies, this is a key component to fine-tune your ammo.