What is the purpose of the “drip rail”?

The drip rail presses on the bottom of the door and fills the ½” gap between the bottom of the door and the curb. The “deflector” protrudes to the interior and helps divert water running down the door into the shower. The flexible “wiper blade” keeps water from passing under the door. If the curb does not have a slight slope to the interior the optional “dam strip” should be applied.