FUJITSU MHW2120BS - Manual (Page 47)

3.2 Mounting
IMPORTANT
Because of breather hole mounted to the HDD, do not allow this to
close during mounting.
Locating of breather hole is shown as Figure 3.3.
For breather hole of Figure 3.3, at least, do not allow its around
φ 3
to block.
Figure 3.3 Location of breather
C141-E249 3-5