Edgeless Safety Cube Receptacle

The Edgeless Safety Cube Receptacle is a game mechanic used within Portal 2's Co-op campaign. It is activated only when an Edgeless Safety Cube is placed into it, after which it will trigger one or more effects within a test chamber.

Trivia
GlaDOS mocks humans for having trouble placing an Edgeless Safety Cube into a receptacle specifically designed for it.