Product review (1 stars): Manufacturing quality comparison
I purchased similar/identical products manufactured and/or distributed by Lambro and by Heartland.  The quality of manufacturing of the Heartland product is far superior (at least with the samples of each product I received).  I have the tools and knowledge to fix the defects on the Lambro, but If you're going to purchase a dryer vent seal, I recommend buying the Heartland brand product, not the Lambro.

Update:
About three years ago, I bought these products to replace the through-wall fittings for the dryer and the vent fan in the laundry room.  They replaced the typical flap-type fittings that are installed on most houses.  The flaps had warped over time allowing cold air (and bugs) to easily enter the vent hose.  Most of the air was stopped by the flap inside the dryer and fan housing, but a little seeped past into the house.  It doesn't take much cold air to destroy the coziness a house might otherwise have.  Anyway, these high-efficiency through-wall fittings stop the air before it ever gets into the vent hose.  Even after three years in the weather, the Heartland and the Lambro products have retained their performance.  These fitting are more efficient and more durable than the flap-type vents that are typically found on houses.  I would recommend them to anyone with the desire to tighten up their home.