All of our innerspring crib mattresses have a 9 gauge border rod, 13½ gauge coil with 5 turns in the coil. The insulator is a thermally bonded fiber pad. The next 2 layers of cushioning materials are foam topper on top and bottom and 100% cotton batting. All foam and innerspring crib mattresses will have nylon reinforced triple laminate covers (the best available in the industry) closed with cloth binding and have 4 brass vents. The high-density foam crib mattresses have an eyelet border as opposed to the brass vents.