Dryer Venting Flex Hose
Comparison of foil and aluminum duct
FOIL FLEX HOSE FLEXIBLE ALUMINUM
"Spiral type multi-ply foil flexible duct" "Semi-rigid flexible aluminum duct"

In compressed state, only 3 1/4" inside dimension

PROS:
  • Easy to work with and install
  • Very flexible

CONS:

  • Much less efficient (a lot of interior friction)
  • Not allowable by most dryer manufacturers
  • Has been known to not contain a lint fire

In compressed state, a full 4" inside dimension

PROS:
  • Maintains a full 4" diameter in compressed or bent configuration
  • Smooth or smoother interior
  • Very efficient and safe
  • Specified by most manufacturers
  • Insisted upon by numerous building codes

CONS:

  • Harder to work with and install
  • Does not have the ability to twist
  Provides a delta of .35 inches of water column pressure
  Provides a delta of .10 inches of water column pressure

Purchase either here

If your dryer's transition hose is the white vinyl type, it is highly recommended
that you replace it with either of the ones above. 
The white vinyl flex is so well known for contributing to fires
that it actually is very hard to find in stores.