The Alma Papa Spring Mattress features dual sids, and a progressive firmness mattress that inverts to accommodate your baby’s increasing weight. Natural rubber latex contours to baby’s natural posture & promotes high breathability. Pocket spring design – undisturbed night’s sleep with long term durability and support. Balancing net – evenly distributes body pressure. Cotton felt – high density cotton layer for extra support & comfort. Unbleached & undyed natural cotton cover - natural sleeping surface for baby.