(Best Option)
Constructed with all aluminum ribbon, DryerFlex fire-rated duct is as flexible as "slinky" foil flex yet stronger than semi-rigid aluminum, making installation easier and every laundry room safer. Quite simply, DryerFlex provides the best functionality of the old transition ducts without any of the defects. DryerFlex always maintains its four inch diameter whether fully extended or compressed. This smooth interior allows the dryer to perform at peak efficiency. It's strong aluminum ribbon protects against crushing and flamespread. Choose DryerFlex for exhaust duct that's safe, efficient and easy to install (Best)