Here's what other sites are saying:
The SPORT Series is a synthetic concept aimed at endeavors that tend to be more "fast forward" and potentially aerobic. Mont Bell Thermawrap Sport Jacket has integrated stretch side panels to allow for a trimmer cut, better ventilation, and greater comfrort while in motion. They have optimized the fibers utilized in our hydro-phobic EXCELOFT insulation to improve warmth and packability by 10%. This series is a lightweight midlayer that delivers thermal performance in less than optimal conditions.