DuoSystem has made Svane a safer buy for the several hundred thousand people who've bought mattresses since we launched this stroke of genius in 1993. Having two firmness levels in one mattress allows you to change the firmness of your mattress once you've bought it. There are times in life when we need a little bit more support. If you find your mattress is too soft or too firm, all you have to do is turn it. This reduces the risk of buying the wrong thing, and also allows couples to choose different levels of firmness for their double bed. No matter what your requirements, DuoSystem gives you freedom to choose and outstanding sleep comfort.