Optimum Power and Flexibility Sidi's proven T-4 has been further developed and completely redesigned for the T-5. This very light triathlon cycling shoe has a twelve- carbon composite sole made of carbon-reinforced nylon with a carbon insert for optimum power transmission and flexibility. This achieves a perfect combination of comfort and rigidity. Wide, ergonomically arranged hook and loop straps ensure comfort and perfect handling in competition. The perforated synthetic Politex material of the upper shoe allows effecient ventilation and is fast drying. Reinforced Heel The reinforced heel keeps the foot in a optimal position and avoids the shoe being deformed by extreme performance or prolonged pressure. The replaceable polyurethane heel pad aids walkability. Microfibre Politex The Politex material is constructed of several overlapping layers with different physical-mechanical properties. The compacted PVC is then coupled to two fabrics (knitted fabric + felt) then film dyed for long-lasting colour retention. Politex offers strong resistance to ripping, laceration, stretching and fading. It is manufactured in strict compliance with European regulations and is a totally 'green' product. Twelve Carbon Composite The Twelve Carbon Composite sole is made with two different blended materials, injected carbon fibre in a matrix of nylon. The Nylon doesn’t absorb water and doesn’t lose rigidity in hot or humid weather or as it ages. The result is a significantly lighter and stiffer sole. Measure Up Your Feet It is recommended that you measure the length of your feet. Place a piece of A4 paper on the floor up against a wall. With your heel approximately 1mm away from the wall, stand on the paper and have someone place a pencil mark on it at the top of your longest toe. Do this with BOTH feet and select the shoe size for your larger foot as listed the in Pushys’ Sidi Shoes Size Chart.