The X stands for Xtreme in this reboot of PUMA's 1980s Running System sneaker that's reconstructed in translucent mesh and pastel overlays. Dimensional sculpting and a mega-exaggerated sole keep pushing the shoe's limits of proportion, texture, shape and even comfort. Style Name: Puma Rs-X Plas Tech Sneaker (Women). Style Number: 5956757. Available in stores.