For best airflow, it is recommended to keep the flexible duct tight, as short as possible, avoid sharp turns and keep the duct as round in shape (do not squash it) as much as possible.
Choose the duct size to suit the exhaust fan and for best airflow, use same size or bigger duct than required by the fan.
Anchor Homes –
What more can i say a duct is a duct!
Anchor Homes –
Not a lot to say. Good quality utility product that does the job well
Anchor Homes –
Perfectly fits the specification and better priced