Zip™ Drives can read 100 MB and/or 250 MB zip disks.  Jaz™ drives can read 1 GB and/or 2 GB jaz disks.  (250 Zip™ drives will read both 100 and 250 MB disks where 100 MB drives will only read 100 MB disks.  Similarly, 2 GB Jaz™ drives will read both 1 GB and 2 GB Jaz disks, where 1 GB Jaz™ drives will only read 1 GB disks.)  Zip™ and Jaz™ drives can be internal or external, depending on your needs.  The Zip™ drive pictured above is an external drive.