The Flash tight has flat lock seams which reduce any friction or irritation so you have as comfortable a run as possible. Mesh panels behind the knees provide great ventilation to keep your legs cool and dry when working up a sweat. 4-way stretch material provides brilliant durability and flexibility that lets your body move without restriction. Stretch Polyamide (18 Lycra) yarn fabric is high-wicking though not cool-to-feel which can be a discomfort with some close fitting leggings. Grip strips prevent the legs riding up when moving so you re comfortable throughout your activity.