evolur Sleep comfort balance innerspring mattress provides the support babies and toddlers need for a good night's sleep. Our stage sleep technology mattress inner core is constructed with extra firm 260 heavy-duty interlocking coils, soft-touch fabric with inverted seams, and a waterproof protection barrier. This mattress is topped with insulated layer foam for ultimate comfort. evolur stage technology mattress is built to fit both a standard full-size crib and toddler bed.