CLIMFEET is a sole that warms your feet warm in winter or refreshes them in summer, without electricity or chemicals, on the principle of the heat pump but using only the mechanical energy of your steps. Very thin and comfortable, CLIMFEET is equipped with 2 layers: one is very flexible, generates cold and the other, slightly less flexible, generates heat. Each layer comprises air-filled cells which are connected to those of the opposite layer by a nozzle. When the foot puts pressure on the ground, compressing the cells of the very soft layer compresses the air to the cells of the other layer via these nozzles, naturally increasing the air temperature through thermodynamic laws (such as when you inflate your bike's tire, compressed air heats the pump). When the foot is raised, thanks to the hyper-elasticity of the materials, the compressed air from the slightly less flexible layer returns to the other layer via the nozzles, which reduces the air temperature thanks to the expansion of the air (as when deflating a tire, the air comes out very cold). CLIMFEET is therefore reversible: simply return them and switch left/right. This is the first time that a sole has been able to warm up without battery or chemical products and also cool down. The cycle repeats as long as the person runs or walks without a time limit. CLIMFEET is intended for athletes, construction workers or cold warehouses, military, firefighters and rescue dogs who are exposed to extreme conditions all day long. CLIMFEET insoles were validated at LIPSEM on about thirty high-level athletes as well as by Vanessa Moralès during the Raramuri in Mexico (190 km), where it exploited both sides: warm side at night and cold side by day.