Directs & centers your cleaning rod & jag through the chamber. This protects both the chamber and the bore from abrasion by the cleaning rod during regular cleaning. "Universal" means that this set will fit most bolt actions and even includes a special adapter sleeve for the AR-15. Precision machined from durable, anodized aluminum, the set comes with interchangeable tips that cover bore sizes from .17 up to .416 and the thread-on nozzles prevent the guide's sticking in the chamber. The guide's specially machined port makes applying solvent to the inserted cleaning patch easier and neater than trying to push a wet patch into the open end of the guide. The Universal Bore Guide Set works with most cleaning rods like Lyman's new Universal Cleaning Rod System and Jag and Brush Set.