|Duofold Mens Varitherm Brushed Back Rib Thermal Top BBP1 fiber content is 100% Polyester. Duofold Mens Varitherm Brushed Back Rib Thermal Top Duofold Varitherm performance base layer helps protect you from the element during high activity sports. Features: Soft, single layer thermal for warmth in cold weather. Brushed inside for added warmth and comfort. Flatlock seams to avoid irrita. Duofold Mens BBP1 comes with 1 Thermal Tops per Pack.