[MrForbes]

It's a differential, as mentioned the square tubing housing is the "input", and the two shafts are the "outputs". If either wheel loses traction, then the other wheel won't be driven, as the slipping wheel will just turn at twice the "input" speed.

Differentials are great in cars, but I don't really see much application in the robots we build. Might be because we don't intentionally push our cars up against other cars, or barriers....which is natural FRC robot behavior.