Hailey Bieber’s golden bustier wasn’t the only thing dazzling on the Met Gala red carpet . While her art-inspired royal blue and gold Saint Laurent ensemble had its moment, she topped off the look with a lacquered, slicked-back hairstyle with a finish so precise, it bordered on liquid, Hailey Bieber used several Ouai products for her glossy Met Gala updo. Getty Images for The Met Museum/Vogue The secret weapon behind it? None other than Ouai’s cult-loved hair oil , a versatile, under-$35 formula. “Hailey’s look is all about balance; it’s structured, but still soft,” Bieber’s hairstylist, Irinel de Léon , shared in a press release of the “goddess” look. Ouai Hair Oil Amazon “The dress has a strong silhouette and presence, so we wanted the hair to feel clean, pulled back and really intentional,” she added. The formula earns its place in the glam room for a reason.…