ASICS Men's GEL-Kayano 15 Running Shoe 100% Synthetic and mesh Rubber sole Impact Guidance System (I.G.S.) enhances the foot's natural gait from heel strike to toe-off Asymmetrical lacing design enhances upper fit and comfort while minimizing the potential for irritation Biomorphic fit upper provides a superior fit and function, ComforDry sockliner provides optimal cushioning performance in a cooler, drier, healthier environment PHF (Personal Heel Fit) features a Memory foam lined heel collar that molds to the athlete's heel, creating a personalized fit Dura Sponge outsole provides superior durability and cushioning with less weight, Solyte Midsole Material is lighter than ASICS' standard EVA and SpEVA, combined with improved cushioning and durability