The dryer exhaust connection is a critical point for the safe operation of every standard tumble dryer. With the prevalence of fires caused by the dryer, it's easy to understand why building code prohibits foil flex and, especially, plastic exhaust hose. Until now, the only accepted solution was the use of semi-rigid which is hard to work with behind the dryer.
Today, DryerFlex is UL2158A listed and meets International Residential and Mechanical Codes for safely connecting the dryer to the external exhaust system. And, it is easy to work with.
The main advantage to foil flex is how pliable it is. This makes it easy to slide the dryer back against the wall. When compressed, however, the inside dimension shrinks down to 3 1/4" and creates a very rough surface. DryerFlex maintains its 4" diameter all the time.
Semi-rigid does maintain its 4" diameter and has a smooth interior. It is harder to work with, crushes easily and is difficult to twist. DryerFlex makes it easier to position the dryer.