All human hair systems eventually oxidize and lighten in color. Red Out Shampoo, when used periodically, will remove those unwanted brassy red colors from dark brown/black hair color.
It's always prudent to maintain a watchful eye on your hair color. It's a dead giveaway that you wearing hair when the unit's hair color develops a few brassy red strands that contrasts against your own hair.
Nip this problem early by using Red Out every 2 weeks.
8 oz bottle.