If you already have a bedstead in good condition, it may be that you only need a mattress to suit your comfort level and budget. However, if you have or need a divan base then the mattress needs to be matched to the type of divan base that you have.
Modern divan bases and mattresses are designed to complement each other in terms of comfort, support and good posture, so it may be necessary with existing, older, divan bases to replace them as, you will not get the full benefit of the features of a new mattress alone, so it is advisable to replace both.
Bed Divans act as bases for mattresses and either have springs which allow the mattress to adapt to the body's contours, or a solid top which provides firmer support. Divan bases offer simple, generic interior style and are also useful space savers for small rooms, as they often have drawers which offer a valuable solution to storage space.