Earthtec Wool Felt Liners can be added to reduce your boot by a 1/2 size when used in the Quatro Boot whole size scale. 6mm thick • Insulated to keep feet warm and dry • Absorbs moisture and keeps shoes naturally odor-free. o Made from natural New Zealand Wool o Helps insulate your feet from the cold ground o Conforms to the shape of your foot and naturally wicks away moisture o Removable and washable