bays are divided into two height specifications, full-height and half-height.

Full-height bays were found in old PCs in the early to mid-1980s. They were 3+1/4 in high, 5+3/4 in wide, and up to 8 in deep, used mainly for hard disk drives and floppy disk drives. This is the size of the internal (screwed) part of the bay, as the front side is actually 5+7/8 in. The difference between those widths and the name of the bay size is because it is named after the size of floppy that would fit in those