The term Bariatric confuses a lot of people, in bedding terms, it implies a mattress that

is suitable for heavier individuals of 23 stone & above. Normally when people are heavier, they are a lot bigger , requiring more space in bed. Also, the heavier you are, the more pressure and wear your joints are under. Bariatric  is not one fixed size, or indeed nor does one mattress suit all. There are different weight limits on different mattresses.  A bariatric mattress can be put onto an adjustable bed, where the head and foot end can be raised or lowered.  Bariatric mattresses can also go onto a reinforced bed base.  they must never be used on a standard bed base. Also in some cases, of the higher end of the Bariatric scale, some individuals need to sleep more ramped up and a Bariatric mattress can go on a ramped Bariatric reinforced wedged base.