Product review (4 stars): Good product, better for rigid pipe not the foil flexible stuff
This is NOT foil flexible hose/duct friendly.  It will work with foil flex duct, but you will create tears in the foil flex duct trying to attach it.  The tailpiece on this vent is designed to be slip fit onto rigid duct/vent pipe, and actual aluminum flexible vent ducting.

Good product, no complaints. I like the way the metal shaft locks onto the plastic louvres.