The J Dewey Rods 13 inches adjustable bore saver rod guide is engineered for precision and durability, specifically designed to accommodate .338 Cal and .358 Cal firearms. This rod guide is constructed to ensure optimal alignment and protection of the bore during cleaning processes. Adjustable bore saver rod guide for rifles with scopes Compatible with .338 Cal to .358 Cal ranges Anodized aluminum rod guide tube featuring solvent port Precision-engineered adjustable aluminum locking collar featuring a durable brass pin mechanism Utilize precision-engineered O-rings to effectively seal the chamber, ensuring solvents and oils are securely excluded from the receiver compartment Substitutes the fastener component with a new bolt assembly Compatible with rifles featuring bolt diameters ranging from 0.695 inches - 0.700 inches Specifically engineered O-rings necessary for optimal performance with .338 Lapua Magnum systems