The unique, patented, American 37.5® Technology has been used in the construction of this Active polo tee. 37.5® Technology helps maintain both an ideal relative humidity of 37.5% and an ideal core temperature of 37.5 degree celsius. When you're hot, the active particles embedded within the material remove perspiration in the vapour stage, before liquid sweat is formed, helping to cool you down. When you're cold, these same active particles use your body's energy to help keep you warm.1.37.5® Technology: This technology helps maintain both an ideal relative humidity of 37.5% and an ideal core temperature of 37.5 Degree Celsius. 2.Dynamic Thermoregulation: When you're hot, the active particles embedded within the material remove perspiration in the vapour stage, before liquid sweat is formed, helping you to cool down. When you're cold, these same actuve particles use your body's energy to help keep you warm. 3.Swift Dry: Swift Dry Technology draws perspiration from the skin; keeping the body cool, dry and comfortable. Especially made for active-wear use.