You will find that the brushes produced by Otis will give you many times the life of most brushes. This is due to the superior construction and engineered features incorporated into the brush, such as a precision thread with no weak undercut. These brushes have a tufcor proprietary core wire that is corrosive resistant, has a tighter twist for better bristle retention, and can be used with all firearm cleaning chemicals. Otis premium bore brushes also have twice the fill as other brushes, the stem is cold welded to the core, and the brushes are filled to the end..