One interesting thing is although the Vault has an IPS4 rating for "protection from momentary immersion and wind-driven rain", it does that without having a separate glass or plastic shield over the face of the iPad Air. Instead, all of the various ports and buttons on the device are neatly sealed away, while the liquids just splash on the bare iPad Air screen. The Vault also meets IPS4 dust ingress protection the same way, while the case provides MIL-STD810G protection against drops.
Lest you think that the Vault's protection makes it impossible to listen to any sounds coming from your iPad Air, you're wrong -- there are specially designed ports that provide excellent audio.
The Vault is not an iPad Air case for the timid, as you will need tools to install it onto your device. There's a small hex driver included (it's taped to the back of the IKEA-like instruction card), and there are a whopping fifteen hex screws that need to be removed and then re-inserted.
Once the iPad Air is locked into the case, it's not coming out unless you decide to remove all of those screws. There's a latching "door" that closes over the screen while in transit, keeping your iPad Air screen from getting splashed on or cracked if you drop something on it. That door folds all the way around behind the back of the iPad Air on a metal hinge; likewise, that hinge makes it possible to stand the iPad Air up for viewing.
The rubber-like covers over the home button, volume toggle, mute/orientation lock, and headphone ports work well, snapping shut (for the ones that open) tightly. The Vault comes in two "colors" -- white and gray or black and gray. There's also a model for the iPad mini with Retina display that comes in additional hues.
One final note: the Vault is guaranteed for life. If it fails before your iPad Air is either completely out of date or can no longer hold a charge, you get another one. That being said, I don't think TUAW readers should try to test the capabilities of the Vault by driving over it with a tank, going scuba diving, or performing any other action it's not designed for.
The Pelican ProGear Vault is not an iPad Air case for everyone, but for anyone who needs good field protection for their tablet it's a winner. The price is reasonable, the case is well-designed and constructed, and it's going to provide the protection you crave.
That protection, however, comes at the cost of bulk and weight. If you don't need the powerful protection the Vault can provide, you'll probably be better served by a case that can provide less protection but weigh less.
If I have one big complaint, it's that the case requires the removal and re-insertion of fifteen hex screws for installation. Other manufacturers have designed protective cases that use interlocking "fingers" of plastic to snap the case together and hold the pieces in place, and they take much less time to install (although they're a pain to remove).
Rating: 3-1/2 stars (out of 4 stars possible)