Forever Foundation Store More Max Size: TwinXL Three-In-One...bed support, foundation and storage. Replaces both the foundation and the steel frame. 9-11 slats with 4 1/2 inch slat spacing and includes foot support slats. Storage and more storage.... twice the storage space of conventional systems. 13-inch high side access with 14 inches of vertical under mattress storage. Four 8-inch legs (glides) total height 16-inches. Additional leg heights available. Headboard brackets included. Fabric deck included for added support, allows the mattress to breathe and filters unwanted allergens. Steel frame naturally resistant to bed bugs. 100% recyclable. Exempt from mattress recycle laws.