Our SUB-0 degree replenish pillow is a hybrid of technical textiles and premium fills, fusing cleanliness with cooling comfort. Experience the reserved response of temperature neutral memory foam topped with a smooth layer of cooling gel. Find additional relief from sleep heat with our cooling cover featuring PureCare's exclusive FRíO rapid chill cooling fibers. FRíO fibers are clinically proven to cool 5x faster than traditional polyester pillow covers. All SUB-0 Degree pillows feature antimicrobial silver chloride to inhibit bacteria, mold, and mildew that cause deterioration, stains, and odors on this product.