This product is suitable for damaged and dyed hair

V: 70 ml

What is hair serum used for? Hair serum is a liquid-based treatment usually formulated using silicones that provide a protective layer over the hair fibre, assisting in smoothing frizz. This smooth layer then reflects the light, which is how serum gives your hair a shiny, not greasy, finish.
A hair serum that nourishes your hair and protects it from UV rays and heat can be used daily.
FYI, they're not the same. The difference between hair serum and hair oil is that hair serum is more of a styling product, which can be used to add shine and smooth hair, while hair oil is mainly used to nourish and improve the health of your hair.
Whenever possible, it's best to apply the serum to damp hair before the rest of your styling products to lock in the benefits but some serums are more than okay to use on dry hair. It's also okay to use a serum throughout the day to touch up the hair, but the initial application should be on clean hair.
Typically, it is okay (and recommended) to use face serum daily. Depending on the type of serum, you may want to use a retinol serum only a couple of times a week to avoid irritation, while something like a vitamin C or hyaluronic acid serum is recommended for daily use.