Bought this for a portable AC unit with a 12” exhaust vent and it work extremely well - it seems very well made and it has a nice feature of staying at the length that you lay it down (since it is accordion-like I expected it would recoil but it didn’t). Only downside is that it definitely needs a better way to connect itself to an exhaust port. I ended up using some bungee cords to keep it in place while I look for a better connection solution. But even with that flaw of the connection point it is still a great buy because of the inexpensive price combined with how well it is made. Would certainly buy this again if/when I need another one.