Product review (5 stars): An excellent investment for cold-weather dryer vents
Tremendous! This stops cold air from blowing back up the vent and keeps your dryer from getting cold. Your clothes will dry faster because your dryer doesn't have to "warm up" to overcome the cold air that has chilled every surface inside your dryer. This also keeps your laundry room from getting cold from the cold drafts.

Installation was really easy! For extra credit, I put a small bead of silicone sealant along the sides of my vent to further insulate my dryer vent and installed a small shim to keep the vent perfectly upright.