Cheap and works. Well, most of them. A few are a bit warped or something so they require lots of violence to remove from the jack. Make sure to test all of them in a non-vital jack before you actually need them.
Not too disappointed, I have bought similar cheap adaptors from different manufacturers and it's always like this. I guess no one wants to manually quality check cheap little fellows like these.
Once you have checked them and binned the few faulty ones, these are great to have.