Mizunos amazing light training shoe updated with improved midfoot fit. U4ic midsole delivers amazing cushioning to weight ratio. The Sayonara delivers mile after mile of light cushioned stable fun. AIRMESH Breathable and Cool. AIRmesh allows each running shoe from Mizuno to maintain a high standard of breathability for the life of the shoe, and allows the foot to stay cool. X10 Durability and Traction. X-10 provides the most durable carbon rubber from Mizuno that allows for longer wear in high impact areas and provides more traction at heel strike. U4IC A unique midsole compound that rides and cushions like Mizuno's ap+ midsole, but is approximatley 30% lighter without any loss of comfort or performance.