Comfort is easily adjusted by flipping this semi-truck mattress over and selecting the soft or firm side. The Dual duty is a 6" combination of soft, medium and firm foams which transforms into an amazing semi-truck mattress. The core of the Dual Duty is firm foam which provides the support of the mattress, while the dual sides consist of a medium-firm foam for those who prefer firmer supported rests and a soft conforming side for a soft sleeping surface. This is the perfect truck mattress for those who need variety: simply flip this mattress to whichever side you or your guest prefers for the night. Made to fit semi-truck models.