|Duofold Mens Originals Ankle Length Thermal Bottom Tall KHW4 fiber content is 100% Cotton inside / 50% Cotton, 40% Merino Wool, 105 Nylon outside. Duofold Mens Originals Ankle Length Thermal Bottom Tall Duofold Originals created the base layer category with the first bi-ply thermals. Each style is constructed to offer unbelievably soft cotton against the skin, paired with the natural warmth of wool for superior thermal insulation. Duofold Originals . Duofold Mens KHW4 comes with 1 Thermal Bottoms per Pack.