This Lee Precision micrometer adjust screw is a large caliber rifle version, complete with a red 4 die storage case. It allows you to keep your micrometer installed on your Lee bullet seating die inside the case. This screw replaces the original on any Lee die, offering infinite adjustability for precise bullet seating depth. Easy-to-read laser engraved divisions represent .001" increments, with an integrated friction ring for smooth, click-free adjustment. It reads like a precision depth micrometer, allowing you to record and return to your settings. Easily transferable to other Lee dies, but with its economical price, you might want one for each.