I am trying to implement a discount code in which it would apply to a specific product but also a specific quantity of that product. For instance, a hat. The discount code applies to all hats but if the customer adds 2 hats to their cart, it would only apply to one, not both. Since the quantity would be limited to that product with a quantity of 1. Im trying to market a free items to drive some traffic to my site and am advertising a free hat with a given discount code, and it would apply to all hats. But I dont want to allow them to enter 50 hats and get them all for free. At the same time, I dont want to limit the card quality itself since I want to encourage them to shop for additional items.