What does the X stand for in RS-X? eXtreme perhaps? eXciting? All of the above? This thrice-eXaggerated form came from a process of stripping away everything from the original RS and building it back up with a stronger mix of materials and a design inspired by puzzles with layers and layers of colours and textures. Low boot. Mesh upper. PU midsole. Rubber outsole. RS-X logo and PUMA Cat logo in contrasting white on tongue label. Embossed PUMA Cat logo and RUNNING SYSTEM on sole - PUMA RS-X Puzzle Trainers in Pink size 5