A Puffy 90s Style with a Chunky Platform Outsole. The Knu Stack starts with our modern interpretation of a classic 90s silhouette—and then cranks it up a notch. With double the height, a puffed up tongue, and a 3D-molded Sidestripe, this in-your-face shoe boasts dramatic style details that blend an icon of the past with today’s bold trends.