Why "HFS?" It might stand for "Highly Flexible Sole," which allows your foot to move naturally, or perhaps the "Happy Face Shoe" for the grin you'll wear when you try it on. It could also represent the "High-Frequency Stride" you'll experience while running in it, or simply the exclamation you'll make when you feel its comfort and lightweight design. Featuring a new lightweight, breathable mesh upper, a tire tread-inspired sole, a silky moisture-wicking lining, and protected tension straps, the HFS is poised to become your favorite road running shoe. And we know you’ll do much more than just run down your favorite roads in the HFS.