Product review (5 stars): When dry vent and outside vent don't meet this is great!
When the dryer and vent don't align this is an easy way to address the issue. I just adjusted it to the offset distance needed. Then I cut off excess (though this isn't required). Then I attached it to the dryer and the flexible duct leading outside.  This device was needed because of  the lack of room between dryer and wall which was to little to allow the flexible duct to be used alone due to crimping of the duct.