The Tipton universal bore guide will help protect the bore and action of your rifle by properly aligning the cleaning rod and reducing solvent overflow. Cleaning without a bore guide can allow the rod to "bow" and rub or gouge chamber and throat of the bore causing real damage and loss of accuracy. Keeping the rod properly aligned not only protects your barrel, it directs the force exerted on the cleaning rod handle allowing tight patches to be pushed more easily. Three interchangeable tips cover most calibers form .17 to .460 note: The tips insert into the chamber and chamber dimensions do not directly correlate to bore diameter, select the tip that provides the best fit for any given cartridge. Protects chamber and bore form damage Ensures proper rod alignment for easier cleaning Reduces solvent leakage into gun&';s action Anodized aluminum tube for durability Integrated solvent port Fits most bolt action rifles and AR-15s Small: Most cartridges .17-.24 (up to 6mm) Medium: Most cartridges .25-.30 (6.5mm- 7.62mm) Large: Most cartridges over .30 (over7.62mm) Compatible with cleaning rods up to .425" diameter Adjustable position sliding collar for bolt actions works with most centerfire rifles Fits bolt diameters .695" or larger AR-15 collar fits securely inside receiver of AR-15 style rifles Inserts and secures into the bolt position The Bore Guide is simple to use. 1) Install the appropriate tip for your rifle 2) Remove bolt and insert guide 3) adjust sliding collar for snug fit into chamber and tighten thumbscrew and your ready to clean