a mattress wherein a plurality of independent yarn based fire barrier fabrics encases a plurality of distinct and unattached interior core structures . the plurality of interior core structures include at least a detached and internally flippable upper comfort layer assembly with a plurality of non - homogeneous foams or filling materials encased in a yarn - based fire barrier fabric and a lower , interiorly disposed support core structure with resilient filling materials encased in a yarn - based fire barrier fabric and a fabric cover . the detachable and internally flippable upper comfort layer assembly may be contained in a user accessible compartment that is fashioned into an outer cover assembly .