Originally only available as an in-salon treatment, Olaplex has a wide range of products from pre-shampoo treatments to serums and oils, with everything from shampoos, conditioners, and masks in between. K18, on the other hand, champions one product – a leave-in repairing hair mask loved by celebrities including Hailey Bieber.

So, if you’re trying to grow your hair but find it just won’t extend past that pre-determined limit, take Smith’s advice: less heat, more nourishment, and regular cuts. It might feel counter-intuitive but will serve you (and your hair) far better in the long run.

Micro-breakage is the reason your hair won’t grow past a certain length