These are not all US sources and are largely manufacturers of the linear or lenticular diffusers you're looking for. I'd suspect once you show a picture of these to your HVAC contractor, he'll understand what you're asking for and obtain them locally from an HVAC supply house that supplies commercial, not residential, projects.
Are you just using these instead of the standard vents? I thought these were more for businesses as air curtains. Where are planning to use them in the HT?
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