Zinus 6 Inch Spring Mattress, Twin Steel Bonnell coils for support. Perfect for bunk beds, trundle beds, day beds Core composition is 1 inch memory foam with 5 inch high density base support foam Only the Highest Quality of Foam-Foam is CertiPUR - US Certified for durability, performance, and content Smartly Shipped - Our patented technology allows our mattresses to be efficiently compressed, rolled and shipped in a box conveniently to your door Worry free 10 year limited warranty Perfect for bunk beds, trundle beds, day beds Only the Highest Quality of Foam-Foam is CertiPUR - US Certified for durability, performance, and content Smartly Shipped - Our patented technology allows our mattresses to be efficiently compressed, rolled and shipped in a box conveniently to your door Worry free 10 year limited warranty