Flip controls may be included in system families, like walls and doors. They may also be added to loadable families in the family editor. When the family is placed in a project, the flip arrow allows you to change the vertical or horizontal orientation of an instance of the family. You can add a single vertical, double vertical, single horizontal, or double horizontal flip arrow. See Creating Loadable Families.
In a project, click a flip control (double arrows) to change the orientation of an element. For example, when you flip a compound wall, you reverse the order of its component layers. Doors with a swing have 2 flip controls: Flip the Instance Facing (which controls whether the door swings in or out) and Flip the Instance Hand (which controls whether the door swings right or left).
Note:
Tip: You can also flip a selected element by pressing the Spacebar.