The regular price for a large, 1-topping Stuffed Crust Pizza is $13.99 in my area (but my local Pizza Hut is offering the deal at $10.99 rather than $9.99. They're also offering a Specialty Stuffed Crust Pizza at $13.99).
They're also highlighting their new crust flavors with the deal by pointing out that you can get any of the ten new crust flavors on your Stuffed Crust Pizza just like you would on their regular pizza.