Dense, durable Nyflex(TM) fiber brushes offer maximum bristle area per square inch to thoroughly clean specific parts of the weapon without risk of scratching bore or the aluminum components. Includes brushes for .223/5.56mm bore, upper receiver, chamber, and bolt carrier. Mfg: Iosso Products SPECS: Brushes - Nyflex nylon fiber. Brush Pak contains bore brush, upper receiver brush, chamber brush, and bolt carrier brush.