With the upper drive cage removed from the case you can see the small utility box that is attached to the back of the drive cage.  This is a perfect place to store rails and screws for the case. 

The lower drive cage has room for four additional horizontally placed drives, this cage is held in place by a single thumb-screw and it also uses the same type of silicon hole bumpers that the upper drive cage has. 

With the drive cage removed you can see get a better look at the opening located at the front of the case where the air is allowed to enter.  The fan that is visible is drawing air towards the power supply which in turn will help cool the lower compartment of the case.

Here you can see the opening located in front of the upper drive cage.  You also have the option of adding an additional fan in the removable fan mounting bracket. This will help cool the hard drives that it is mounted in front of as well as provide additional cooling for the entire case.

Looking at the inside of the side-panel you can get a better idea of the how the sandwich design works on the side-panels.  With one sheet of aluminum making up the outside skin which is attached to the plastic inner-liner and then a second aluminum skin is attached.