This leave-in is built for people trying to grow out or maintain longer hair that keeps snapping or fraying — especially hair weakened by color, heat styling, or simply length itself, where the ends are the oldest and most damaged part of the strand.

Redken markets it across hair types, but the target concern is breakage and split ends specifically, not general dryness or curl definition, and it's designed to be used with the matching Extreme Length shampoo and conditioner rather than as a standalone fix.

Hair doesn't stop getting longer because growth slows at the scalp — it stops looking longer because the oldest, most processed length keeps breaking off at the ends. Extreme Length's leave-in is built around that specific mechanism: Redken's Length Care Complex combines biotin with soy protein to reinforce the hair shaft, which is why the brand's own figures for the full system are framed around breakage reduction (up to 81%) and less visible splitting (78%) rather than a faster growth rate.

As a leave-in rather than a rinse-out step, it's meant to stay on the hair through the day, which matters for a product whose job is ongoing mechanical reinforcement against snapping and split ends rather than a one-time conditioning boost.

Use as the last step after washing, and don't rinse it out.

• Apply to clean, damp, towel-dried hair
• Leave in — do not rinse
• Style as desired
• For the full breakage-reduction results Redken reports, pair with Extreme Length Shampoo and Conditioner

What this treatment does well:

• Backed by Redken's own figures — up to 81% less breakage and 78% less visible split-end appearance when used as a full system
• Leave-in format means no extra rinse step
• Lightweight enough not to weigh down longer hair
• Targets a specific, common problem (breakage at the ends) rather than being a general-purpose treatment

Things to keep in mind:

• Reduces the appearance and rate of breakage — it does not make hair grow faster, since biotin's role here is strand strength, not follicle growth speed
• Best results are tied to using it alongside the Extreme Length shampoo and conditioner, not on its own
• Contains fragrance and preservative ingredients (chlorhexidine digluconate, quaternium-33) worth considering for sensitive scalps