Spira - Vortex II (Silver/White/Burndt Orange) - Men's: The Vortex II runner combines the WaveSpring in the heel and Spira's unique XLEVA with flex grooves in the forefoot, creating a highly stable, flexible and well-cushioned ride. XLEVA is formulated to produce superior rebound and durability versus standard EVA. The outsole is made of a high abrasion carbon rubber for durability. The upper design uses the strategic placement of reinforcements and a firmer density medial post for runners who have pronation issues or need extra support. This model combines WaveSprings cushioning and energy return technology in the heel with stability features and offers a flexible hinged forefoot plate for a smoother ride. Shoe weighs 13.5 oz.