Product review (5 stars): Actually work!
Shockingly these actually work! I have two heat vents in a very large master bedroom and unfortunately the way it's laid out I can only have my bed over the two heat vents. If we have the furnace at 67 at night it will be 63 in my room in the winter. I had to jerryrig these a little bit to get them to work but now my room stays at 66.5. Vast improvement- can't wait to see how it helps with the air conditioning!