Sneak Suits are the covert ops extension of the encounter suit
The electromagnetic adaptive camouflage system
The biggest reason that Amerikka Command survives to plague the Atlantic Federation, the only reason the ACPS hasn't destroyed the Python Pirate Syndicate, is their mastery and sharing of shroud technology.
You come upon a ruined building in the back section of a city park (or other out of the way area of the city). The ruins are fairly overgrown. All that is really standing is a doorway and its frame. If you pass through the opened door, you travel to a different world. If the door closes, there may not be a doorway back to get you back.