The Fluid Ride mid-sole technology gives you a more efficient and comfortable ride on longer runs. Plus, you get an improved toe off with strategically-placed flex grooves on the out-sole. The Gel Cumulus 16 also helps you run more efficiently when fatigued, with a Full Length Guidance Line that guides your foot through the gait cycle. Every landing is cushioned by rear-foot and fore-foot gel which absorbs shock and gives you a cushioned ride.