"The courthouse building was still there, too, but it looked like it had been turned into some sort of mall, with a fancy, smoked green glass entryway that led to dozens of underground shops. The names of the stores below flashed on a 3-D electronic display, places with names like World O' Transponders and Hydrators Unlimited."
—From Back to the Future Part II by Craig Shaw Gardner (quote, page 24)

World O' Transponders was a store located in the Courthouse Mall in downtown Hill Valley in 2015.

Judging by the name, it can be safely assumed that this business stocked transponders for use in flying vehicles traveling on the skyways.


See also