But Selkirk makes a flexible listed vent that looks just like that. It has b-type connectors at either end. The pics don’t show the top, but the bottom looks proper.
I have seen these on a number of installations and the solid collar at either end is not removable.
Here’s one from a home I took a few weeks back. There was a similar connector on the furnace about 15 feet away. I was not inspecting this home, and it does look like someone cut off the the other connector and screwed it to the hood.
We have mostly gas water heaters than electric, and only sometimes these cheap DIY flexible pipes are in use. The proper vent pipes are obvious when seen in person. Next time you see one, press it with your thumb and watch it crush/push-in, where the proper ones are much more rigid. Once you see the cheap crap in use, you will never mistake it again!
And there are flexible B-vents. My larger point is that flexible does not mean it’s a dryer vent.
I’ve seen dryer vents used in place of B-vents, clearly no good. When they have that smooth, fixed, riveted collar on the end, chances are they are used in a listed application.
