5.25-inch external drive bays can hold several different types of hardware. A CD burner, like the one shown above, is just one example. CD-R disks can store around 700MBs, (or 700,000,000 bytes), of information. The recording speed rating associated with CD-R drives varies up to 54x. It varies up to 32x for CD-RW drives. For each 1x that a CD burner is rated, it can record 150KBs of information in one second. For example: a 10x CD burner can record 1,500KBs of information per second. A 20x CD burner can record 3,000KBs of information per second. A CD-R drive can read and write information, but it cannot erase it. CD-R disks can be used in any CD-ROM player. A CD-RW drive can also read and write data, but it can also erase the data and rewrite new data, which is useful if you save something and later wish to remove it. CD-RW disks are not as compatible as CD-R disks, and are limited to CD drives capable of supporting the MultiRead standard. CD-RW drives can use both CD-R disks and CD-RW disks.