Adjust to your make and model of bolt action rifle. Just select the proper caliber, remove your bolt and adjust to fit your action. The rod is guided straight into the barrel without dripping solvents and contaminates into your action. Use the 13 inch model for scoped rifles. All Dewey Bore Savers have built in milled solvent ports.Features17 to 22 Caliber will not fit in 17 HMR, 22 Long RifleMay require some custom fitting for some riflesReplaces firearm's bolt, guides cleaning rod into bore.Chamber-sealing O-rings help prevent solvent from entering action.Adjustable for length, 13" models intended for rifles with long scopes which would require additional clearance.