7-8 inch Coil Safety innerspring - This mattress is 7 to 8 inches thick and has 13.5 gauge wire coils, bonded fibre foam around the coils, 60/40 poly blend duck cover, and 14 to 24 pounds of cotton, depending on whether you get the twin or the full mattress. These mattresses meet the new federally mandated CFR 1633 Open Flame Compliance <view picture>