In order to choose the size of your Mattress topper, you must know the size of your mattress, both must be equal. Therefore a 200x200cm mattress topper will fit perfectly to a 200x200cm mattress. So check your measurements. If you choose a down matress topper with a thickness of 6cm, consider checking the size of your sheets to ensure that they will suit the total thickness of the mattress and the mattress topper. The mattress topper 200x200cm is a supplement of comfort to a firm or medium matress, it will assure you an unsurpassed softness. All those who have tested our mattress toppers in a luxury hotel with Dumas Paris products recognize that it is incomparable! However it will not give a second life to your mattress... Synthetic mattress toppers are fitted with elastics to hold onto the mattress, while the down mattress topper holds on by itself because of its higher weight.Finally, it is important to know that the natural comfort mattress topper is not washable in a traditional washer machine or in the dryer. That's why it should be protected like a mattress, with the protective cover that we offer: this product is of course washable to ensure perfect hygiene to your mattress topper.