Experience weightless conditioning and strength with the Acidic Bonding Concentrate Fine Hair Duo, with Shampoo and Lightweight Liquid Conditioner. ACIDIC BONDING CONCENTRATE SHAMPOO Redken's Acidic Bonding Concentrate sulfate-free shampoo is Redken's most concentrated all-in-one formula for strength repair on all types of damaged hair. Featuring Citric Acid, this shampoo contains a concentrated bonding care complex that reinforces weakened bonds within your hair to improve hair strength. • Comb