The cover sheets are made of soft trico quality. This means that they less wrinkle then weaved cotton and that they are easier to put over the mattress. Furthermore, they have an elastic band so that they will stick to their place. The sheets are available in a lot of colours so that they you can combine with your different bed sheets. Also perfect to use for a pram! size S: 40x80 cm size M: 60x120 cm size L: 70x140 cm