The Mini Bonnel Springs used in the Kidtex Spring Mattresses offer excellent spinal support and comfort. Space between the spring lattice allows for increased airflow that helps regulate the child's body temperature. Each spring core is encased within a high-grade, dent-resistant foam as well as an additional thick felt layer for added comfort and longevity. The top cover has a waterproof surface on the reverse side to protect the inner layers of the mattress. Comes with a removable and washable cover. Kit for Kids mattresses does not contain any PVC or plasticizers, ensuring kindness to both the environment and your baby.