Combining the Ultra Jags and Best Bore Brushes into one convenient 26-piece set gives you the ultimate storage system for your brushes and jags . Neatly organized in a durable hinged box with marked cavities, it's easy to select the correct jag and brush for the job. Since 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 (does not include 20 caliber). All jags and brushes have 8-32 threads (17 caliber has 5-40 threads and is a standard bore brush)