Following shearing at the farm, woollen fleeces are placed together in "sheets", that is to say large sacks containing about 20 rolled fleeces each. These sheets are bulky yet are light (weighing about ) and convenient for the small farmer to transport to his local wool collection centre. Here they are opened for grading and sorting into one of several dozen different qualities, based on breed of sheep, which dictates fineness of wool, and physical condition of the wool, for example damp dirty or stained fleeces will be graded lowly.