The Mirage Mattress is made from a Visco Plus a superior grade 85 density visco elastic material. It delivers an incredible combination of comfort allied with far higher levels of pressure relief. Visco Plus has a unique open cell structure and is far less reliant on your body heat to remain pliable across a wide range of temperatures for a more consistent supportive and comfortable sleep experience all year round. Equivalent of 1600 springs in a King Size mattress.