Introducing the Altra ALTRA Experience Flow Trainers. The Experience Flow From Altra Performance Trainer Is All About Your Running Experience, Like Walking On Clouds: Smooth, Effortless, Lightweight And Efficient. Glide Through Daily Workouts, Enjoy Street Or Trail Running And Go About Your Weekly Program. Featuring An Engineered Mesh For Greater Breathability, Combined With A 4Cm Heel Drop, Giving The Shoe Its Rocker Shape Geometry And A Responsive Compression-Moulded Foam Midsole For A Lightweight Performance. Sole Material: Rubber Cushioned Heel Counter Standard Fit Stack Height 32/28 4Mm Drop Engineered Mesh Material: Non-Leather