There’s also the even smaller M.2 format and PCI-Express drive format, which tend to be thin sticks with bare chips measuring around a few inches long.
There are three different storage drive sizes you’re likely to encounter, and they all mount and connect differently. Generally, hard disk drives (HDD) are the larger 3.5-inch size, while newer solid-state drives (SSD) adopt the smaller 2.5-inch size. There’s also the even smaller M.2 format and PCI-Express drive format, which tend to be thin sticks with bare chips measuring around a few inches long.