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 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 (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).