Linen fitted sheets cover the mattress – the elastic band holds them firmly in right place. Their function is to protect the mattress and ensure smooth and soft surface. When purchasing linen sheets, it is important to have the right dimensions of a mattress – the length, the width and the thickness. As fitted sheets must pull snugly over the mattress and not be easily pulled off, the right dimensions matter a lot. The wrong size simply will not be able to go neatly round the corners, and will not stay in place.