This One-Sided, Firm Mattress was constructed for stomach sleepers looking for a supportive sleeping surface at an affordable price. Foam encased for additional edge support, this mattress has 2 inches of Support Foam, 2 inches of Ultra Support Foam and a VertiCoil Innerspring Unit. The no-flip design gives you the benefit of having all of the comfort layers between you and the spring unit for maximum comfort. The Messina Full Firm Mattress and Box Spring by Corsicana