This is an entry in our Disneyland 101 Glossary: Disneyland Resort definitions in under 101 words, from Mouse Brief.
Safety is a top priority at Disneyland Resort, so each attraction is equipped with seating and restraint systems. Some rides have metal bars that pull down across your lap once you are seated. You may be asked to lower the bar yourself, or it may lower automatically. Cast members may ask you to demonstrate that the bar has been properly fixed in place by having you push on it before the ride begins.