The tapered bronze bristles of the Otis chamber brush scrub the chamber, neck and shoulder. The steel bristles at the base scrub the star chamber of the locking lugs. The brass stem is cold welded to the core, and the tip is folded, not cut. The chamber brush has a standard 8-32 thread.
It is available in either 5.56MM or 7.62MM (essential for anyone that shoots a 7.62MM rifle).