Casper Sleep Foundation - Queen size. The Casper foundation is engineered to provide excellent support under your Casper mattress but can be used with other mattresses in place of a traditional box spring. Engineered with solid wood and rigorously tested for durability and proven to stand up to years of sleep. Slats are positioned a perfect four inches apart for optimal support. Ships in a compact box and can be easily assembled in minutes - without any tools. Designed and assembled in the USA.