The Zero Gravity Serene is the firmest of this collection. The base of this mattress will feel strong and supportive. The transitional layer is comprised of a High Resolution 3.0lbs denisty foam for maximum support. The top layer is our Serene Airflow foam. The very top of the mattress will feel comfortble but over all this mattress will feel firm. The mattress is finished with our Bamboo breathable fabric.