Indicates how well a fabric allows moisture vapour (sweat) to escape from the inside to the outside, helping to regulate body temperature and prevent clamminess during activity. A higher rating means better breathability, allowing more sweat to escape. Higher Ratings (8,000+): Indicate excellent breathability, ideal for high-intensity activities and warmer climates where moisture management is critical. Moderate Ratings (4,000-8,000): Suitable for various activities, including hiking, cycling, and general outdoor use. Lower Ratings (Below 4,000): These ratings are suitable for activities with less physical exertion, like casual wear or light work.