The tfr (total fouling removal) kit is made with black heavy duty long lasting nylon bristles.These brushes were made specifically for your ar-15 and built tough so they can be used repeatedly.It is compatible with standard american cleaning rod with #8-32 threads.The kit includes: upper receiver brush, bolt carrier brush, bore brush and chamber brush.Thread Pattern: #8-32Type: Brush SetQuantity: 4 Per PkgBristle Type: NylonMaterial: Brass CoreSuitable For: Firearms