Patent ID: 8117700

Claim:
A mattress comprising: a core unit having first and second side portions spaced in a parallel relation, and third and fourth side portions spaced in a parallel relation and perpendicular to each of the first and second side portions, the core unit comprising: a first cover defining a first internal region; and a plurality of core cartridges removably disposed within the first internal region, each of the core cartridges having a firmness characteristic, the plurality of core cartridges comprising: a first group of core cartridges having respective firmness characteristics based on a first group of parameters, the first group of core cartridges being disposed between the first and second side portions and between the third and fourth side portions; and a second group of core cartridges having respective firmness characteristics based on a second group of parameters, the second group of core cartridges being disposed between the first and second side portions and between the third and fourth side portions so that: the second group of core cartridges is disposed between the first group of core cartridges and the fourth side portion, and the first group of core cartridges is disposed between the second group of core cartridges and the third side portion; wherein the second group of parameters is different than the first group of parameters and thus the combination of the respective firmness characteristics of the second group of core cartridges is different than the combination of the respective firmness characteristics of the first group of core cartridges; and a topper unit removably coupled to the core unit, the topper unit comprising: a second cover defining a second internal region; and a first topper cartridge removably disposed within the second internal region.