Brooks Men's Beast Running Shoe 100% Mesh and synthetic Rubber sole Diagonal Rollbar, a high-density post at the medial arch, is engineered for pronation control, creating a smoother transition from heel strike to toe-off. MoGo polyurethane midsole provides a soft, cushy feel that lasts without sacrificing stability for more cushioning, more energy return and less fatigue. Forefoot and heel HydroFlow liquid cushioning eases shock on muscles and joints. Leather and mesh upper, polyester microfiber upper lining and sockliner, Ortholite insole, polyurethane midsole