The Plexi window is firmly attached to the side panel and the fan is held in place with plastic push-pins. It has a decently long power wire with both 3-pin and 4-pin pass-through power connectors. An overall view of the rest of the interior shows the standard grey painted steel chassis.
Rather than a plain brown cardboard box NZXT has included a small pouch to store all the accessories in. In addition to the standard mounting hardware there are also some wire management ties, side panel lock tab, three sets of hard drive rails and a multi-language user manual.
A closer look at the front of the case reveals that not just one, but the top two 5¼" bays are blocked by the front LCD panel display. A plastic tray is installed in the very top spot to house the electronics and wiring. The second slot down could actually be used as an internal-only 5¼" bay, although there are no tool-less locks installed as in the other three spots so you'd need to use screws. In the lower section there are two 3½" bays with tool-less locks as well, and a hard drive cage turned sideways that offers three slots for drives with the included rails. The cage is removable, with two screws holding it to the motherboard tray and two in the bottom of the case, and the front intake fan is mounted behind it. It's strange to see an LED fan with a solid black housing; normally these are molded from clear or some translucent-colored plastic.
The rear of the case again shows the seven expansion slots with tool-less riser clips. These are the type that have the release catch at the top and rotate 90° up and out of the way so that cards can be installed. The exhaust fan is just a standard black non-LED fan. The grommeted openings for water cooling are at the very bottom of the case, which might cause some issues with tubing length depending on where you would mount an external radiator. I've seen these openings at the top of other cases but never actually used them, so just something to consider if you're planning on using liquid cooling. The back side of the Guardian 921 reveals very few openings for passing cables through. Basically the spot beside the 3½" bays or through the hard drive cage are the only areas available.
Time to install some hardware.