A Hide-A-Bed also known as a “Sofa bed” or “Sleeper sofa”. The mattress offers support to the sofa base and can be unfolded from the sofa and used as a great guest bed. These mattresses are size specific to the individual sofa specifications. The standard thickness is approximately 4-1/2”. Please measure your existing mattress to ensure you are ordering the size that will best fit your sofa. There are two styles to choose from an innerspring coil and a foam construction.