Base Layers are the first layer of clothing you put on. These next-to-skin layers are designed to move moisture away from your body. Warm weather base layers and undergarments consist of the lightest weight short sleeve T-shirts and briefs. For cool or cold weather base layers are available in different weights or thicknesses. Long sleeve T-shirts, mock turtlenecks and leggings worn under gear keep you warm while wicking away sweat. Middle layers often made of fleece and polyester blends are worn between the base layer and outer foul weather gear as insulating layers. These varied layers of top and bottoms will keep you warm when the tweather turns colder while wicking moisture away from the body to keep you dry. The thicker the mid layer, the warmer you will be.