Product review (5 stars): SUPERB!
If you have you ever tried to get a 4" pipe to fit a 4" pipe, you will love this product.  After months of messing around with adaptors and pliars, I finally happened on this product which is pliable enough to snugly slide over my 4" vent.  Also, its flexibility really deters kinks that act as traps inside the vent hose.  This product is worth every penny!