Rachel Bilson's Ultimate Hair Essential Only Costs $9

Even though The OC’s last episode aired in 2007, Rachel Bilson will eternally be cool girl, Summer Roberts, in our hearts.

Times may have changed, but the 43 year old’s casually tousled strands will forever be top of our hair inspiration list.

But as we recently discovered, Rachel’s signature style was more of a happy accident than it was intentional.

“My hair has always been undone,” she recently told Allure. “It was never pretty. I don’t like put-together hair. For me, it’s always been the messier, the better.”

“I guess you could call that a natural look, but my natural hair definitely needs some tweaking,” she joked. She went on to say that her hair has been a lot finer ever since the birth of her daughter, Briar Rose, nine years ago.

“It is so thin now; my ponytail is like the size of a penny. It’s very depressing. I’m already so low-maintenance with my hair, but I am definitely still in my mom-bun era,” she explained.

Despite her insistence that her hair doesn’t naturally boast that west coast wave we love so much, she actually only really swears by three core hair products…

Rachel Bilson’s top 3 hair essentials

“My routine is really bad—I don’t do anything to my hair unless I absolutely have to,” Rachel admitted.

“I don’t wash it every day, because that just does not work for my hair or the frizz that comes with it,” she shared with the mag. “But for shampoos and conditioners, I love R+Co [Television Perfect Hair Shampoo] ($49 from Adore Beauty) [and R+Co Television Perfect Hair Conditioner] ($49 from Adore Beauty).”

The duo are infused with a variety of botanical extracts that help to smooth frizz, improve moisture levels, as well as enhancing the overall shine and body of hair.

As for her hair styling routine, Rachel keeps things simple and sticks to a tried and true classic that she knows will work in any scenario.

“I know this is going to make me sound like an old lady, but I still swear by [L’Oréal Paris] Elnett [hairspray] ($8.99 from Chemist Warehouse),” Rachel admitted. “It’s great. It brushes out, and it’s a miracle.”

Beloved by hairstylists for it’s flexible hold and micro-fine mist, this pick is a fantastic option to seamlessly transition your hairstyle from day to night.