The Fleet is a lightweight short sleeved button-up made from a high-performance oxford fabric that blends 37.5A(R) fiber with soft, durable cotton to provide a high degree of performance and comfort.Featuring 37.5 vapor management technology, The Fleet outperforms when facing temperature and activity extremes - keeping you cool when your core temperature rises. In contrast to traditional technologies that wick moisture away from the skin after liquid sweat has already formed, 37.5 absorbs moisture and pushes it out into the atmosphere when it's still in a vapor state. In other words, 37.5 doesn't deal with sweat, it helps keep you from sweating in the first place. 37.5 also isolates odor molecules, does not rely on chemical finishes and never washes out.