Standard bed sizes are based on standard mattress sizes, which vary from country to country. Bed sizes also vary according to the size and degree of ornamentation of the bed frame. Dimensions and names vary considerably around the world, with most countries having their own standards and terminology. In addition, two mattresses with the same nominal size may still have slightly different dimensions, due to manufacturing tolerances, amount of padding, and support type. In almost all territories, standard beds are rectangular but other shapes, notably circular, may be obtained by special order.