Lightweight Breathable Materials for a '2nd Skin' fit and feel; Roomy Toe Box allows toes to spread naturally and comfortably; World Leading High Tech Polymers delivering lightweight high performance and superior energy return; Recycled Materials keeping sustainability in mind to help keep waste out of landfills; Stack Height: 37mm (heel) / 32mm (forefoot); Heel to Toe Drop: 5mm; Weight: 8.1oz (M9); Best for Road Running, Tempo Runs, Race