The Hicon pancake style plugs are great, so I had high hopes these stereo plugs too. Unfortunately my experience wasn't that great.
Good things first. The metal shell is extremely sturdy. It's a solid piece of metal and nicely finished with matte black paint. The threads are excellent too. They're more fine than in other connectors of this type, which means that they're not going to loosen up easily. All the other parts are robust too. Unfortunately there's no bend protection boot, so just use some heat shrink if necessary.
And then the bad stuff, oh boy. The plastic insulation tube is weak. It's thin, hard and brittle. I soldered and assembled a bunch of these, and when I opened them up for inspection, the insulator had badly cracked on every one of them. My guess is that the provided tubing is either too long, too weak or both. These plugs can be somewhat difficult to solder, especially if you're using large diameter, high quality cable. There are no holes on the terminals and there's little room for even a small soldering iron tip. Strain relief is also insufficient due to thick metal and dull teeth. You have to push the teeth in with sturdy pliers to make them bite and it's still doesn't work that great.
I ended up replacing the plugs and won't be buying these again. They're not bad... it's just that there are better plugs available for a lower price.