Filson brought their original Jac-Shirt into the world nearly 50 years ago. With the weight of a jacket and the versatility of a heavyweight shirt, it was built to withstand hard use for years on end. This Mackinaw Wool Jac Shirt has all the heavyweight durability and warmth of its predecessor, plus, it's constructed with 100% virgin Mackinaw wool, and finished with two dual flap pockets at the chest.