Keeps solvents from dripping into action and prevents excessive cleaning rod contact with the rifling lands closest to the chamber. Includes 3 interchangeable chamber tips to fit .17-.416 caliber. Aluminum action collar fits .695"/.700" (17.65mm/17.78mm) diameter bolt actions of any action length. Threaded brass pin locks the guide into the action in place of the bolt to allow proper cleaning from the breech.