Vionic Avery Metallic Iridescent Slip-On Sneakers. Part of the Vionic Pro line, these shoes feature a metallic, shimmering iridescent leather upper with a textured, "crackled" finish.  Key Features Design: A classic slip-on sneaker silhouette with elastic twin-gore panels for easy on-and-off. Support: Designed with Vionic's signature orthotic technology to provide comfort and arch support. Safety: Features a slip-resistant "Vio-Grip" outsole, making them suitable for professional environments where floor traction is important.