A typical 3.5-inch low-profile (1-inch high) HDA, also known as "half height", has the following physical dimensions.
Physical dimensions:
- Height 1 inch
- Width 4 Inches
- Length 5.75 Inches
Other form factors in popular use on the Macintosh line are full-height drives, meant for use on the earliest all-in-one Macintoshes and the third-height drives supported by the mounting brackets used in the Workgroup Servers like the Power Macintosh 8550.