The scalp is a real blind spot. The part line and the crown get direct overhead sun all day, nobody puts lotion there, and dermatologists find skin cancers there routinely. Scalp melanomas are diagnosed later and do worse — partly because nobody is looking.
A mist is the only practical way to cover it. You cannot rub a lotion into a scalp without ruining your hair, so almost everyone skips it. This solves the delivery problem, and that is the entire point.
It is a real sunscreen, not a UV hair serum — actual FDA-regulated filters, water-resistant for 80 minutes.
Reviewers confirm it prevents the part-line burn, which is the specific job.