Men's Brooks® Glycerin Flex: Take control of every stride in your Men's Brooks Glycerin Flex, designed with innovative flexibility that moves naturally with your foot. The engineered flat knit upper delivers breathable comfort and a smooth, adaptive fit, while DNA TUNED cushioning provides plush landings and energetic toe-offs. An asymmetrical midfoot flex groove teams up with podular lateral forefoot zones to give you targeted flexibility and support right where you need it. Your Glycerin Flex blends premium softness with a fluid, body-driven ride.