As much a jacket as it is a heavy shirt, this updated Mackinaw Wool Jac-Shirt is warm, weather-resistant, and highly breathable. The Filson Original Jac-Shirt, introduced nearly 50 years ago and built with soft and warm wool, serves as a heavy shirt or a light jacket. Its earned the enviable reputation for being the most versatile garment in a sportsmans tool kit. In 2016 Filson re-imagined that iconic classic, creating their beefiest jac-shirt with an entirely new level of warmth and protection. Built with the same wool thats sheltered foresters and sportsmen from wet and cold weather for over a century, this heaviest jac-shirt is built to stand up to the elements for years on end. Only the longest and strongest fleece fibers are selected for the Mackinaw Wool, which are then spun into dense yarns and woven in an uncommonly-tight weave that turns away the weather and lasts for decades.