The FuelCell foam provides a propulsive sensation that assists in propelling you forward. The upper is made of a lightweight engineered knit material with no sew overlays. The gusseted tongue is specifically designed to provide a sleek fit. The lace closure allows for adjustability and a secure fit. The drop of the shoe is approximately 6 mm, but please note that due to variations in the development and manufacturing processes, this measurement may not be exact.