Superside Down Alternative Pillow. The special Superside® gusset pillow features unique side gussets and a curved corner design that pushes the fill to the center, ensuring maximum comfort and support. FILL TYPE: Silky and luxurious with a true down like performance, loft and feel. Adjustable support. Blown, fine denier, gel fiber, 28 oz. FABRIC: 233 thread count, 100% Cotton, Barrier Weave® woven to block dust mites and allergens. CLEANLINESS: Hypoallergenic. DESIGN: Superside® Gusset. CARE: Machine wash and dry