Still pointed at the abyss, and now switched off and on mid-conversation with a rival crawler.
The selector is what makes every portal trick of the hour possible: the cart portals stay tuned to The Abyss, and anything that touches one is gone. Nobody dares turn the hanging cart's portal off while Princess Donut has her head in the hole. When Prepotente starts hammering it from the far side and then calls out, Katia Grim rises on stilt-like legs to reach the controls and shuts the portal down on Carl's word, ready to flip it straight back on — the flicker and the sudden view down into The Space In-Between being the first time the two crawlers see each other.
Carl assures Imani C that these portals are stout enough that nothing can get through, without actually knowing whether that is true.
A control panel mounted high on a rail cart, reachable only by someone tall or willing to grow.
The switch that decides whether the floor's escape hatch is plugged or open.