Product review (5 stars): Probably one of the nicest dryer vents out there
This is probably one of the nicest dryer vents out there.  It's made of sturdy plastic and worked well for my application.  On the backside there is a circular slot that accepts the end of a 4" vent pipe.  I struggled to get a new piece of pipe into the slot as the pipe I had was just slightly too large, and there was nothing that locks the pipe onto the plastic.  Oh well.  As it turned out the vent pipe in the wall was flattened so I had to improvise.  Maybe some day I'll upload a photo of how I made the connection.  In the mean time, I'd buy this same vent again if I needed one.  The louvered vents are junk.  They get plugged up to easily, the louvers get stuck open, and the plastic disintegrates in the sun.  I hope this one holds up.