Original sentence: Although usually not supplied with the machine, floppy disk drives of the 5¼ inch (1541, 1551 and 1571) and, later, 3½ inch (1581) variety were available from Commodore
Edited sentence: Although usually not supplied with the machine, floppy disk drives of the 5¼ inch (1541, 1551, 1570 and 1571) and, later, 3½ inch (1581) variety were available from Commodore