The deep side part with mega volume at the roots—it’s the cool-girl hairstyle loved by models, actresses, It girls, and anyone who’s taken a scroll through Instagram lately. The problem is getting it to stay in place long enough for you to take your #hairgoals selfie. We feel your pain. So we consulted the experts behind celeb hairstylist Jen Atkin’s website Mane Addicts and asked them to show us how to execute the coveted side-flip hairstyle so it lasts all day (and all night) long.