KAZE APPLIANCERound Exhaust Ventilation Duct with Backdraft Damper (4-inch)

The idiot that installed my bathroom fan tossed this part and just taped the vent hose to the square hole. Without the flap cold air comes back in in the winter.

didn't fit right. also doesn't close fully. whats the point of the flap if it doesn't close?

good