Matt,
All that is, is the original cover on the OEM air filter box which I painted and cut the sides off. I couldn't use the whle box as I had the aftermarket filter. That striped cover just sat on top of the battery to cover it up during shows. It would come/fall right off if the car was moved as it's not fitted/tied/glued down at all.
There's all kinds of aftermarket dealers selling battery covers. Here's a couple of them for you:
http://www.gotmypt.com/html/battery.html
http://www.fastlanegrafix.com/Batterycovers.html