Vans Classic Slip-On Stackform Shoes. The Classic Slip-On Stackform refreshes our original slip-on silhouette with an even chunkier take on the platform aesthetic. Constructed with a 34 mm sidewall height, this platform shoe elevates a classic favorite while bringing a new “Off The Wall” style to your look. Along with sturdy canvas uppers, the Classic Slip-On Stackform is finished with traditional elastic side accents, supportive padded collars, and signature rubber waffle outsoles. Imported.