If you choose to use a mattress for the Stokke® Bounce ‘n’ Sleep Daybed other than the one provided with the product, it is your responsibility to ensure the mattress is of the correct shape and size to cover the complete base surface of the Daybed, with gaps between the edge of the mattress and the side of the daybed not exceeding 4 cm./1.5 inches and the thickness of the mattress not exceeding 5 cm./ 2 inches. Failure to do so presents a suffocation hazard for the child.