Whether a product will qualify depends on whether production activities in the US are "substantial in nature." US activities can be substantial in nature even if a significant amount of production occurs outside the US. When evaluating the substantiality of US activities, bear in mind that the 20% safe harbor is not a mandatory threshold for qualification. You and your tax advisors should evaluate the significance of the US-based activities (e.g., do they add significant value or functionality to the product that is ultimately sold).