The threading is marginal, it requires precision and a bit of patience to screw them in, otherwise the threads will skip. They haven't shown any problems, but I wouldn't let someone at a gas station screw them in.

I bought them black, after 3 washes they turned silver-gray. (at least they match the rims in both cases)

They are nice, but they don't stay in place for the simple reason that they get stolen. Every time I've tried to put similar ones (and I've put all kinds and colors, black, silver, blue, bought from everywhere, from Skroutz, from a store, from China...) they have been snatched. Meanwhile, the last ones I had on, due to wear and tear, had become a disgrace, full of exhaust fumes and dust, and had collected so much dirt that they were unrecognizable. How the thief who took them realized they were blue aluminum, only a god knows. So a thousand times the simple plastic ones!

Nice to the eye up to a point.. after 3-4 washes that intervened.. they discolored to a great extent... resulting in them appearing more silver than black...

To be screwed well, they must be exactly in the right direction, if they are inserted crookedly, you have to take them out and try again, this is not particularly pleasant. And as correctly mentioned in a comment here, after a few days they start to discolor gradually... They are small in size, so don't expect them to make a visual difference, there is nothing special compared to regular caps. In short, completely useless in terms of appearance (they are barely noticeable), color (it fades), and usability (difficult to put on and take off).

Very good quality and stable. On the downside, they fade after a while, perhaps after using chemicals for cleaning on rims. They also require a detailed start when screwing in, but they do indeed screw in securely.

Very good!! Sparkling color! It will show over time for durability. Although they seem reliable.