Yellow Xanax Bars are effective fast-acting oral prescription antianxiety medication that helps to treat, manage, and control anxiety disorder, panic disorder, and phobia. Furthermore, Yellow Xanax Bars is the 2Mg of Alprazolam pill that has the imprint of “R039” on one side of the bar, and its street name is “Yellow School Bus” or “Yellow bus.” You can divide Yellow Xanax Bars into four quarters; one quarter contains 0.25mg.