Two types of mattresses come with multiple firmness levels but the ability to benefit from more than one firmness level at the same time is only available in a dual sided mattress. A split firmness mattress is ideal for couples who have different sleeping preferences. On a split firmness mattress, they can have their cake and eat it, too. Each person gets to enjoy the firmness level and feel they prefer in a single Queen, King, or California King mattress.
One example is this Helix mattress that provides a medium-firm feel on one side and a softer feel on the other. Air mattresses will also provide adjustable split firmness levels.
A mattress with double sided firmness levels is better suited to guest rooms where you have sleepers with different preferences sleeping in the bed. One side of the entire mattress will be firmer than the other side. The mattress can then be flipped over so that the preferred firmness level is provided. A flippable, double sided mattress can also be useful if a firmer mattress is needed temporarily, such as during recovery from surgery. Once the requirement for the firmer mattress is gone, simply flip it over to enjoy your preferred firmness level.
This Latex for Less mattress is flippable. Layla and Zenhaven also offer flippable mattresses.
Some manufacturers have introduced mattresses that allow the customer can open up the mattress and adjust the insides to change the firmness level by rearranging the layers or moving foam pieces around like a jigsaw puzzle. We haven’t seen one of these options stay around long enough to make our list.
There are other ways to increase or decrease the firmness of a mattress such as adding toppers or changing the type of foundation being used.