The Rex Air comes with heavily perforated Technomicro for maximum air flow. The boot is equipped with 3 steel cable adjustable closures with Sidi’s exclusive TECNO3 PUSH rotor. The PUSH button allows the arm of the dial to be lifted perpendicular for more closing pressure. The shin and ankle mechanisms pull from the center allowing a symmetric closure. The instep mechanism ensures a snug yet comfortable fit. Sidi’s proprietary Technomicro is used to construct the upper. Elastic panels are added in the key front and rear of the boot flex areas for maximum comfort. The foot is surrounded by Cambrelle®,a synthetic lining material that wicks moisture away and keeps your skin dry and less likely to blister. A single ankle support brace joins the internal and external ankle joint for more support. In the outer lower part, the ankle support brace is equipped with air vents which can be operated by an aerodynamic shaped button. The ankle support brace is made of a nylon material infused with fiberglass fibers. Small slots on the joint’s central part allows perspiration and air dissipation. Nylon innersole with removable arch support pad Double stitched in all high stress areas. All bolt on parts are replaceable. Dual compound sole. DuPont polymer toe shift pad. Perforated Teflon treated nylon lining. Asymmetric shaped heel cup is equipped with a soft fixed insert on the internal side of the boot for better adherence and contact with the bike. The toe slider is made of nylon reinforced with fiberglass and is fitted with a new air intake and an innovative alloy insert. Padded Achilles area is very comfortable.