The Hanover 12-In. Tranquility Memory Foam Twin Mattress is made of a 2-In. solid memory foam top 3-In. Comfort Layer and a 7-In. foam base which is a high density foam that provides long-lasting durability and support. The removable washable mattress cover provides a plush sleep surface and lasting comfort and durability. The entire mattress is protected with a 20-year limited warranty. All Hanover mattresses are CertiPur certified which means they are made without ozone depleters PBDE flame retardants mercury lead other heavy metals formaldehyde or phthalates.