The Acton Igloo triple-density boot liners are constructed from an inner layer of polypropylene felt that insulates and wicks moisture away from the foot, a middle layer of polypropylene and wool for insulation and more moisture wicking, and an outer layer of Radiantex to reflect body heat in and cold out. This boot liner can also be used with other footwear products designed for a 9mm-thick removable felt liner.