I was using this for my water heater as a nipple connection to join two different pipes. At first, I used PFTE tape around the threaded connections. However, no matter how much tape I used the connection would develop a slow leak. I had to remove the connection and redo this with a big slab of the T+2 thread sealant compound. Although it initially did leak slowly, eventually it looks like the compound took and the leak was plugged. Not sure how confident I am with this connection yet, so I would be watching this for a bit to make sure it does not develop any leaks.
This item also looks very similar to other 304 stainless steel nipples on Amazon, although this one is slightly more expensive. Many of the other ones listed have complaints of the threads not being made properly (not true to size) so it gets difficult to ensure a good seal. While I am not sure if this product is equivalent (they do look identical), it sounds to me that this is the issue I am having with this product as well.