Now, flippers are used on every single pinball machine.
The flipper is thin, with the base, which is further from the center of the playfield, being thicker than the tip, which is near the center.
More recently, games have added upper flippers, which are flippers higher up than the standard two at the bottom of the playfield.
The flipper was originally 2" long, but has been 3" long for about the last 30 years.
Flippers are used to control the ball. The control techniques are called flipper skills.