How many Time Gears are there in Pokemon Mystery Dungeon?

There are two Time Gears in Pokemon Mystery Dungeon: Explorers of Time, Explorers of Darkness, and Explorers of Sky. They are:

* Time Gear: Found in the future, allows access to the past.

* Space Gear: Found in the past, allows access to the future.

While not technically a Time Gear, there is also the Key of Time, which allows access to the past but acts more like a key than a gear.