Simply wear for your desired Activity (check product for Temp rating)
Layering with basepro:
BasePro + Winter shell -5˚F to 60˚F
Basepro's + Glacier or Shadow jacket: -20˚F to 50˚F
Basepro's + Tundra or Storm: -30˚F to 45˚F
Basepro's + Vest + any Jacket: -40˚F to 40˚F