Product review (5 stars): THIS IS THE ONE! (not GE 8 ft. Semi-Rigid Dryer Duct)
I was one of the suckers that made the quick trip to my local hardware store to buy a dryer duct, like I had in years before. Unfortunately, the local "Big Box" store only sells the "semi-rigid" which will dent and break easier than you can with your thumb through a piece of tinfoil!

Then I bought the "Proflex"perfect!! Open it slow, which you'll do if you've experienced any problems with a semi-rigid duct, and it will fit easily into place!!  The clamps, as others have previously said, are pretty worthless.  I used my old clamps which still work fine.