Product review (5 stars): good product
This product works as designed.  I use the vinyl for venting a bathroom fan.  I stay away from the foil type because they'll eventually rot out from the moisture.

Be careful not to tear it when installing.  either on nails from a subfloor or on the aluminum collars that sometimes have a sharp edge sticking out.

to bad none of the box stores carry vinyl ducts; not sure why.