Advanced ProjectsA(R) is our series of products designed and developed with the most advanced textile and construction technologies available in the world. They are designed to perform at an elite level for a wide range of activities including cycling, running, hiking, and climbing. The base layer fabric is a soft lightweight knit with extreme 4-way stretch that incorporates 37.5A(R) vapor management technology.Advanced Projects Seamless Base Layers represent the future of next-to-skin technology. In a recent study done at the University of Colorado in Boulder, 37.5 was found to increase peak performance by 26% over traditional performance wicking apparel. To our knowledge, there is no other available technology that performs as well as 37.5 for high-activity applications.Seamless construction enables the torso section of the base layer to be knit in one piece minimizing bulk and the potential for friction spots. This allows multiple fabric thicknesses to be incorporated into the garment without the need for sewn panels. Seamless Base Layers breathe exceptionally well to keep you cool when you're warm and warm when you're cool.