Safety sensors are a vital part of installing a garage door. Background: safety sensors are attached to the rails on which the garage door rolls up and down, and it is about six inches from the ground.
It has the function of reversing the direction of a garage door when a person, especially a child, or an animal moves beneath it while it is closing.
This will ensure that nothing and no one gets injured, and also cut costs in that area should someone get hurt. You can even test it at home, by placing a broom or a toy beneath it to see if it reverses.