Replacement Boot Liners: Quilted 80% Wool Felt, Natural Gray (636) - 1 Pair Felt Needle felt (80% wool blend, 20% synthetic fibers), Thinsulate, Cambrelle 1 pair, 3/16 inch (5 mm) thick Quilted finish and heel reinforcements High-performance cold protection, durable cushioning, excellent moisture and sweat wicking This is a unisex replacement liner and intended for boots with existing removable liners. Please see our sizing specifications to ensure the right fit for you.