CPO WOOL JAC-SHIRTTaking design cues from the heavy wool shirts issued to Petty Officers, the CPO Wool Jac Shirt is the newest addition to our overshirt legacy that spans five decades. The U. S. Navy issued heavy woolen shirts to its senior enlisted men beginning back in the 1930s to satisfy the need for a warm, protective shirt that would serve in the unforgiving weather found at sea. Filson has made heavy wool overshirts for service in the wet and cold Pacific