Product review (4 stars): Love, hate and acceptance.
I'm actually a return customer having bought this for my previous home as well. If you have a short attention span, you can correctly assume that I like and recommend this product and stop reading here.

Now that all the idiots with short attention spans have left, I'll tell you about the frustration parts. With their short attention spans, they'll never get it to work without duct tape and tears. Ha! Let's all take a moment to laugh at them. Continue reading when you're finished.

So, the sleeve and the plastic connector fit great, as long as you don't happen to have a 4 inch duct inside of the sleeve. I have yet to get any standard dryer duct or accessory that it will fit properly and fully seat in the plastic. The sleeve will push back and you'll probably be generally frustrated. No worries. As long as you get the sleeve and plastic to mate firmly, it shouldn't slip off of the duct. If your duct is beat up and out of round, your struggles will intensify. I guess you should have been more careful with your duct, huh? That's how we learn.

Struggles aside, once it's on, I generally leave it on and use the collar to disconnect the flexible duct. It could be better executed, but still the best dryer duct product that I've found. Way better than wedging my fat carcass behind a dryer trying to get a hose clamp on or off. I accept this product warts and all.

Once you've struggled and put it on, please pause a moment to think about those short attention span people and how much worse it was for them. Laugh again if you feel the urge.