The active particles in 37.5® technology enhance the performance of waterproof breathable fabrics by accelerating both vapor diffusion and liquid evaporation. This technology actively works with your body to keep you dry and comfortable.


Your body already has the ultimate thermo-regulating system: skin. The perspiration vapor that comes off of skin during activity cools the body when working hard. In fact, each gram of evaporated sweat releases 580 calories of stored heat. A key to comfort is removing moisture from your clothing layers. Unless this water vapor can be removed it builds up in clothing and creates a clammy microclimate next to skin. 37.5® technology works to enhance the body’s natural thermo-regulating system to keep you comfortable.


The active particles in patented 37.5® technology enhance the comfort and performance of waterproof/breathable (W/B) garments. Traditional laminates rely on a large water vapor concentration difference across the membrane as the main mechanism to create diffusion and drive excess moisture from your microclimate out through the clothing.

This requires a buildup of humidity within the microclimate. Typically, water vapor doesn’t start moving through W/B fabrics until the relative humidity in the microclimate next to your skin reaches about 70% relative humidity.1 At that point you are already uncomfortable, as the optimum relative humidity in your microclimate is around 35%-40%. 37.5® technology adds a unique mechanism to increase the driving force and remove water vapor before it builds up. The active particles in 37.5® technology are desiccant materials that work with your body to attract moisture vapor, capture your Infra-red (IR) energy and add surface area to the membrane. The combination of these physical properties increases water vapor diffusion and accelerates evaporation, thereby reducing internal vapor concentration and condensation. The result is a much more comfortable user experience.


  • 37.5® technology improves moisture vapor transmission (MVT) and drying time by 30 to 100%. This helps your body more efficiently maintain an ideal core temperature, enabling you to perform better, longer
  • 37.5® technology reduces condensation formation
  • 37.5® technology adds durability and feels better next-to-skin, eliminating the need and unnecessary cost of a separate liner
  • 37.5® technology is made with naturally derived materials
  • 37.5® technology gives a drier touch while accelerating vapor transport and eliminating the plastic/sticky feel

References1Comparison of Sweating Guarded Hot Plate and Upright Cup Methods of Measuring Water Vapor Permeability, Phillip W Gibson, 1992 Waterproof Breathable Fabric Technologies: A Comprehensive Primer and State of the Market Technology Review, Alan Dixon, 2004