Product review (3 stars): Not for every use...
The product is well made, although it "unwinds" quite easily.  You have to treat it gently to keep from ruining it.  I ordered this item because my portable a/c requires a 5" duct and they're hard to find.  Unfortunately, it turns out that it wouldn't fit my a/c.  The "screw on" coupling on the a/c actually needs the white plastic vent, not a metal one. Because I'd damaged the product before I figured that out, I didn't bother to return it (after all, it was my fault).  I just wanted to post a warning to other a/c users that, if you have a screw on coupling, this might not work for you.