Vionic Astor Preston - Men's Slip on. A slip-on loafer with an unexpected edge, the Astor Preston’s premium leather upper and twin gore detail make it the perfect casual for work or weekend. An athletic-inspired rubber outsole lends versatility and durability. Genuine leatherskinned removable insole. Natural Alignment with Vionic's Biomechanical Footbed. The orthotic-grade footbed supports your feet from the ground up.