Product review (5 stars): Works great, just follow directions.
Yes, it's plastic. Yes,  the pieces could come apart in the duct if you don't do it right. Just follow the directions and you'll be fine.  Just don't be stupid...
* don't reverse direction on the drill and the pieces with unscrew.
* don't force it into massively clogged vents and it won't get stuck and won't break.