.223/5.56MM CHAMBER AND BORE CLEANING The AR15 Brush Combo contains the critical components you need to keep your AR15 chamber and bore carbon free. It contains a star chamber brush and star chamber mop for cleaning inside the hard to reach star chamber. Star chamber pads help collect left-over carbon while applying the perfect amount of oil or solvent. The .223/5.56mm bore brush scrubs baked on carbon from lands and grooves.