BoreSmith, Cal 357, 9, 380, 38 Special, Pistol Bore Brushes, 10-Pack, Nylon Our standard brushes have nylon filaments, and they are made for pistol/revolver length chambers Standard 8-32 threaded connectors are made of non-abrasive aluminum Carbon-steel twisted core wires give our brushes superior strength that resists bending Comes packed in clam shell for safe and easy storage Nylon filaments do not react with ammonia based solvents to discolor patches