Taking a closer look into the compartments we can see the first as already mentioned is a HDD docking slot. This does require a AHCI capable motherboard though. There are rubber
mounts so that the drive can sit without scratching/sliding.
The other compartment has magnetic feet that allow the cover to sit over the mesh panelling. The idea with this cover is to dampen out any noise from a top mounted fan, It also acts as a dust shield for the system - This cover only really works if you don't have a fan installed though as typically you would have a top mounted fan dissipating heat from the case (exhaust), not blowing air in (intake). An intake fan in this position could well hinder airflow.
Top compartments for hot swappable HDD docking and top mounted fan
Underneath magnetic cover is a mesh panel for top mounted fan
Usually I wouldn't show the underside of a case within a case review but since the H2 has something quite different underneath I wanted to show this. We have a series of rubber mounts to prevent sliding and in the middle a large section of filter material for the PSU and if you choose to mount a fan at the bottom of H2 (on the inside).
The underside of H2 with large fan filter area