Super Quiet Register Booster Fan for 4" x 10" Register Holes, Smart Register Vent with Dual Intelligent Thermostat and WIFI App Control, Heating Cooling AC Vent Fan (White)

Are they the old style square ones? I assume they're talking about the rectangular ones like this: https://a.co/d/0507D4Cu I have one, it does make a difference, but I don't know if it's going to be 10-15 degrees of difference. The first thing I would do is rent one of those insulation blowers from home depot (they are free with a purchase of like ten or more bales) and blow in another foot of insulation in the attic. You will be amazed the difference that that makes.