The first goal of this base layer is to move moisture away from your skin while adding minimal insulation for those cool days when your riding intensity is high enough and your outer layers are warm enough. The areas covered by the bibtight around the waist and up the back can get hot, so we used a lightweight PrimaLoft® fabric to help even out the temperature. This base layer works best when in contact with the skin, so both fabrics are very stretchy and the cut is slim. On extremely cold days we'll use this as a first layer under a Flanders Warm second base layer, or under a thermal jersey. It's very effective at moving sweat away from the body.