Hon&Guan 3 Inch Duct Connector, Plastic Duct Flange Vent Systems 3 Flange for Heating Cooling Ventilation Vent System-2PCS.

Decent quality and easy to install. Worked well with 4" flex dryer hose.

I bought this to use with a modular custom 6" exhaust vent duct for a portable AC unit in a dedicated, climate controlled media equipment closet, and it worked perfectly. My first portable AC unit in the closet quit working after about 5 years, so I had to replace it. Unfortunately, the new AC unit came with a different type of exhaust hose attachment, even though both units were LGs, and I stupidly built the first exhaust duct to last forever. Since I needed to recreate part of the exhaust duct because of the different AC exhaust hose attachment types, I upgraded the 6" inline exhaust fan I'd been using to help push the exhaust about 20' to an external wall, as I wasn't sure how much longer the original fan would last and they're relatively cheap. Additionally, I wanted to install a one-way butterfly baffle to prevent any cold air from coming back into the closet while the AC exhaust wasn't running, which I hadn't done before. And, because I've recently begun to fully appreciate that everything will eventually need to be replaced at some point, I wanted to make the exhaust duct as modular as possible, because connecting flexible ducts to portable AC exhaust hoses, inline fans, and one-way baffles is a time consuming nightmare. So, I added an insulated adhesive gasket between the two pieces of this duct connector, and superglued some screws onto one of the pieces, then used nuts to hold them together. This way, I won't have to tear the whole exhaust duct apart again just to replace one part of it, should something fail again (portable AC, inline fan, baffle, etc.).

Fit perfect. Met my needs and expectations

Very good product

A portable air conditioner needs venting to the outside for heat transfer. The window hardware that came with my unit was cheaply made and broke. So I had too use a little "redneck engineering" to make it happen.Thus flange is EXACTLY what I needed to feed the vent duct through it. Once installed, I sealed it up for a weatherproof fit.In case you're wondering, the nylon stocking I used as a bug shield expands when the A/C is running. I know it looks funny, but that's what redneck engineering is all about -- makeshift designs that work but look stupid.

I’m using this collier for part of the air intake on my diesel garage heater. Works great.

Wonderful place to buy odd things that some of us need...Thank you for being there when I needed you even a fair price for quality manufacturing!!

Doesn't fit the duct fan it was recommended with and, because the extension off the flange fits snugly into a standard 4" duct pipe, it really doesn't fit anything. Cannot connect the duct fan to it and cannot mate a standard 4" duct coupler to it in any way because it is too small.