The Grundens Forecast Insulated Vest is specifically created to provide high levels of warmth without the bulk of traditional synthetic insulation. This makes it an ideal outerwear option for chilly weather. With its technical features and PrimaLoft Insulation, the Forecast Vest is an excellent alternative to natural down. It has low water retention, which means it retains its warmth even when wet, allowing you to conserve body heat in any weather condition.