Best suited to people with fine, flat, or thinning-looking hair who want a shampoo that cleanses gently while supporting the appearance of fullness at the root. It's a retail hair-care product appropriate for home use, though its scalp-rebalancing pH claims will matter most to people already dealing with scalp sensitivity or early thinning rather than those simply wanting extra volume.

Its differentiator is the low-pH, azelaic-acid-driven approach to scalp care layered under an otherwise ordinary sulfate cleanse — most volumizing shampoos rely purely on lightweight polymers or protein coating to fake fullness, while this one also treats the scalp's acid balance, which Redken frames as foundational to the rest of the system's density claims.

1. Apply to wet hair and scalp.
2. Massage into a lather, focusing on the scalp.
3. Rinse thoroughly.
4. Follow with Redken Acidic Grow Full Densifying Conditioner.

Pros:

• Low, acidic pH formula is designed to keep the cuticle sealed during cleansing rather than lifting it the way higher-pH shampoos can
• Azelaic acid targets scalp acid-mantle balance, a root-level approach rather than just coating the hair shaft
• Still delivers a full sulfate-based lather and cleanse, so it performs like a familiar shampoo despite the treatment actives
• Designed to pair with a matching conditioner and serum for a complete density system

Cons:

• Contains sodium laureth and sodium lauryl sulfates, so it isn't suitable for anyone specifically seeking a sulfate-free shampoo
• Effects are cosmetic — the appearance of fuller, denser hair — not a treatment for genuine hair growth or hair loss
• Best results are tied to using the full system (conditioner, serum, spray), not the shampoo alone
• Fragrance and citrus oils in the formula may not suit fragrance-sensitive scalps