Expandable depth control (up to 5.50") provides extra depth adjustment to help short throw projectors get the throw distance needed to achieve a great picture when a whiteboard is mounted over a chalkboard. With these two Dedicated Wall Adaptor Box models that are compatible with short throw projector arm models SMART Arm 600i, SMART UX60 and Hitachi A100WALLARM2, there is a solution ready to help create the perfect picture in virtually any setting.