It has the rotor closing, that guarantees a more precise fit.It has a wide aperture that makes the put on easier.These shoes are comfortable and efficient during long races.Tested by Italian Athletes.SST - Soft Touch Technology.EFC - Ergonomic Fitting ConceptUD CARBON SOLE "FRECCIA TRICOLORE"SIZE: 40 - 48HALF SIZE: 40½ - 45½UPPER: Microfiber Soft Touch - PebaxSOLES: Full Carbon UD Air System Sole High Stiffness. Full Carbon UD Speedplay sole (40-48)WEIGHT: 253 grams (half pair size 9)SST - Soft Touch Technology. With the right choices in research, materials and exclusive surface treatments, Vittoria guarantees its products will look unique showing their beautiful design and cutting-edge technologyEFC - Ergonomic Fitting Concept. From the Vittoria R&D department comes our Ergonomic Fitting Concept (EFC). A complete range of products developed for your feet, head and body; ergonomically designed and tested to improve both performance and comfort.UD CARBON SOLE "FRECCIA TRICOLORE". CLEAT FIXING SLOTS: allow a more precise cleat adjustment. Replaceble heel pad. GRIP: cleat grip is guaranted by a special paint finish around the cleat fixing area. AIR INTAKES: air intakes keep the foot fresh and dry. SOLE:3,4 mm UNIFORM THICKNESS: this structure guarantees the maximum rigidity where needed and, at the same time, less stress on the foot.