Fantastic Vents are available both with and without the fan reverse feature. This is so the upfitters can conform to the aforementioned codes if their vents happen to be too close to the fan. As several have said, the manufacturer would be glad to provide the parts you need to add the feature if you don't have it already.
Formerly: 2005 Airstream Interstate (Sprinter 2500 T1N)
Now!: 2014 Great West Vans Legend SE (Sprinter 3500 NCV3 I4)