This is our most accomplished triathlon shoe to date! The perfect balance between the triathlon specific needs and raw performance without sacrificing comfort. Exo-Jet Carbon outsole --> Designed to increase stiffness and provide excellent toe to heel airflow. CFS (Custom fit System) --> 100% moldable upper, breathable laminated microfiber leather complete upper for ultimate comfort, maximum power transfer and support. Heel retention strap (HRS) --> Maintains heel in place while power stroke, maximizing power transfer. Molded toe box bumper and heel cup --> Maintains the shape of the shoe during transition while providing ventilation and stiffness. Reverse power belt --> 2 reverse velcro straps reinforced with Kevlar band. Super fast in transition, without compromising support. Increased stiffness for maximum power transfer. Cycling mesh upper --> Amazing ventilation without loosing stiffness. Weight (size 41/1 shoe) --> 310 g/11 oz. 2 reversed velcro straps closure --> Easy slip-on and quick to attach. Ergo Air interchangeable.