The Sinclair Two-Piece bore guide system helps the shooter get the best possible alignment of the cleaning rod to the bore by using a guide within a guide. The guide body goes into the action and seals the chamber with an O-ring, like a traditional bore guide. A separate guide slides into the rear of the guide body to provide a slip fit for the cleaning rod. The tight-fitting 8" insert prevents the rod from flexing and keeps it centered, so it will not contact the rifling while you clean. Choose the guide body to fit the cartridge your rifle is chambered for, then select the insert with the inside diameter that fits your rod. Both guide body and insert are machined from Delrin with rubber O-ring seals to prevent solvent from getting into the action. Bore guide bodies are made to fit the Remington 700 and other rifles with .700" diameter bolts. Inserts Sold Separately