Lab Rat
Common55.3%Story
Acquire the fully powered Aperture Science Handheld Portal Device.
Story-forced, so you can't miss it. Up to Test Chamber 11 you've only had a single portal colour to work with; at the start of Chamber 11 you pick up the full dual-portal device (both the blue and orange portals) and it pops the moment you equip it. Carry on as normal.