Product review (5 stars): This works great if you have the right fittings already
This works great if you have the right fittings already. Take the advice other reviewers have offered and use aluminum tape to seal all edges. I used it to seal the dryer connection and wall connection because of poor fittings. It is no smaller than the other ones listed, It is adjustable by cutting it with tin snips. I expected this one to be smaller and the 0-18" is relative. It cannot go to 0" if it is a periscope; you essentially use it as a connector and cut all extra size off and still have to tape all the pieces; if that's you're intended purpose it will not be helpful for you.