Product review (4 stars): Overall Very Pleased
It works very well and I'm satisfied but I have a love/hate relationship with this duct.

Love: Thin metal makes it easy to cut to the size needed.  Narrower than standard round 4" duct and space saving.  The round hole was at the bottom and not at a 90 degree angle.  Home Depot only had the ones with a 90 degree angle.

Hate: Needs to be taped and sealed all around because it will leak air.