Abstract: A mattress has a perimeter rail having a head end, a foot end, and two sides, each having an inner surface, and at least two substantially parallel rectilinear sections. Each section comprises an array of springs whose tension is selected to provide a predetermined firmness for that section. Each adjacent pair of sections is urged into a spaced-apart relationship by a spacing means, where each spacing means comprises a flexible spacer. The flexible spacer restricts or substantially eliminates the translation of movements between the sections of the mattress, while avoiding the use of uncomfortable separation means.