mirrored offset: verify left-hand and right-hand before installation fitting orientation & field verification mirrored offset left hand right hand wrong way backwards duct fitting offset direction compare the offset to the airflow direction, plan view, elevation, and the direction you will be looking before it leaves the ground. a fitting can have the right rise and run and still be mirrored. i matched the rise and run, marked upstream, and checked the plan-view direction. this offset still moves opposite the coordinated route-do you want it remade or is the drawing view reversed?