I found this randomly…
It’ll be offered online soon. Looks a little better than the blowup pack already.
http://www.gbfans.com/community/viewtopic.php?f=90&t=20137
http://protoncharging.com/gb/2010/05/12/proton-pack-backpack-holy-crap-proton-pack-backpack/
http://ghostbustersnews.com/?p=1807
