Product review (5 stars): It works!!
This is a great product for the right application.  I am lucky my dryer is on pedestal so I could remove the drawer and slide under the dryer to get all the access I needed to fit the periscope and to tighten the clamps.  I don't know how I would do it if my dryer was on the floor because I have very little room to work with in my closet.  It solved my problem, the flexible duct was not working for me as my CHECK VENT light was on all the time despite my duct being cleaned.  Now everything is OK and I am happy.