Cynthia Rowley is bringing her style to Birchbox! The subscription-based service offers users a box of new beauty product samples each month, and those who join before June 30th will receive a Rowley-designed and curated package. Birchbox doesn't usually reveal the contents of its boxes, but we do know one item that Cynthia Rowley picked to be inside her swirly case— Redken Shine Flash! "This gives my hair a sheen that remains polished throughout the day," the designer told InStyle of her choice. To join the company's $10-per-month subscription service, head to Birchbox.com.