... :2003, ISO9001:2008 CEFeature:1)Injection-molding manufacturing process means no cutting; therefore, no microfissures to weaken the bracket. for smooth, rounded edges ... and denist convenience.With following specifcation for choice: 0.022" No Hook 0.022" 3-Hook 0.022" 3,4,5 ... -Hook 0.018" No Hook 0.018" 3-Hook 0.018" 3,4,5 ...