Heat insulating layers like the Spika Chase Puffer Jacket are the ultimate cold weather insulation layer while on the move, providing essential body heat regulation in the colder months. Heat insulating layers retain body heat by storing warm air between the baffles, while still remaining packable and light weight. If you get too hot, simply unzip the front zipper to dump heat if the jacket is doing its job too well. For cold weather conditions while glassing or those cold winter hikes the Chase puffer will keep you toasty.