Product review (5 stars): Great quality and extended length
After recently purchasing a new washer and dryer, it was time to replace my old crunched/bent duct.  I wanted to get a longer vent/duct that would allow me to pull the dryer out a bit farther for cleaning and maintenance and the Dundas Jafine Semi-Rigid Dryer Duct (8-ft) was a good answer.  My item arrived bent and damaged, but Amazon took care of the situation as always.  This is the semi-rigid variety, meaning it's more difficult to bend and crush and is great for airflow.  But if you are going to install an 8 foot length, you will need room for it contract, so you might want to look into a dryerbox that goes into the wall or if you are stacking your dryer or have plenty of room to install your dryer then it's not a problem.  It's 8 feet extended and about 27 inches when compacted.  If you have the space and options for the semi-rigid duct, go for it.  Although it says that no clamps are required, I would always recommend using clamps so that it doesn't slip off.  Clamps are cheap and simple to install.  A plastic extension piece and elbow are included to help with installation.