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The highest rated breathable hiking shoe models (page 10)

Breathable materials allow perspiration, evaporated by body heat, to escape. Fabrics come with different levels of breathability from low (0-5000) to high (15,000+) which should correlate to the level of exercise that is being done. For example, the level of breathability necessary for low-intensity exercise will be under 5000g/m2/24hr (grams of water vapour per square meter).