Conveniently packaged 13-piece caliber-specific set of Ultra Jags means you always have the right jag at hand. Contained in a durable, hinged box with marked cavities, it's easy to select the correct Ultra Jag for your particular application. Because they are caliber-specific, you can be assured of an optimum fit to your firearm's bore for efficient and thorough cleaning. 17 to 45 caliber. All jags have 8-32 threads (17 and 20 caliber have 5-40 threads).