5" Low Profile Heavy Duty Foundation for Platform Beds and Thicker MattressesThis is a 5" low profile heavy duty foundation. These are commonly used on platform beds where a lower mattress height is desired. Today's mattresses are generally thicker than older mattresses, so low profile foundations are also used on older beds to lower the mattress height so that the mattress doesn't "swallow" the headboard and or footboard. Sometimes a bunkie board is preferred over a low profile foundation which is a solid thin base or "board"