I actually have four of
these.
I first bought 2 of them about 8 months ago. I've subsequently bought two more about 4 months ago. With one of the first 2 that I bought, the only problem I ran into was a leak on the SS elbow joint with the bottom of the conical. I went ahead and disassembled all of the joints for all of the conicals and replaced with new teflon tape. I have not had any issues since.
The top lid the top of the fermenters have a rubber gasket that fits around the each. When closed, you get a tight rubber on rubber seal.
Over the last 8 months, I've brewed 4 batches of beer and currently have 2 batches of wine and one of brew aging in them. I have not had any issues with leaks.
They are pretty nice. Before owning these, I have never owned any other conical, so I have nothing to compare them to. However, I do work for a biotech company at manufacturing plant so I'm around SS equipment, similar in nature to these, and in my opinion there isn't anything about them in terms of material and construction that "looks off" to me.
In addition, the guy who sells them (ebay name: homebrewhousediscount) is on the level, communicates well, and ships quickly. I didn't have any problems.
I'm also not affiliated with this seller in any way. The post here asked for a review from somebody who has experience with these, so I posted.