It saved me from the screw clamps.
It fits very well and the weights don't move.
I bought another pair.

They hold the discs well, which I had some doubts about due to the shape of the F28 bars, and so far they haven't come off the regular bars, but also small bars, although I haven't tried weights over 90 kilograms. If they were a little tighter, they would be perfect. 4.5 stars from me

The best thing about these collars, everyone should buy them for the bar, as they greatly facilitate the process and are very tight, without fear of the plates coming off.

I got them for dumbbells. They work great for exercises parallel to the ground. Not so much for vertical exercises with heavy weights. However, they solved my problem of constantly screwing and unscrewing to change the plates.

I bought them for my house because I had the iron bars and the "put on, take off" was driving me crazy, and it was removing everything except the discs, and even though I was a little afraid, in the end, they are indestructible, nothing moves!

It does the job for which it was designed. Some of them I have had for a year and they haven't loosened at all, some are new and there is no difference from the older ones. Very satisfied. For exercises that require standing dumbbells - as Ziiiv says - indeed, from a certain weight and above they start to give in, but the same would happen with any collar, except for the screw-on ones. They are not designed for this use.

As long as the dumbbell is parallel to the ground, it is very good. However, when performing exercises that require the dumbbell to be upright, with more than a certain weight, they start to give way, with the result being dangerous. It is not recommended for exercises with upright dumbbells (e.g. chest pullover).

The strength that holds the plates is moderate, there is a fear that they might come off and loosen even more over time. Not suitable for heavy weights

Very good quality that stabilizes the discs on the dumbbells/bar without needing constant intervention like with screw-on collars. After 3 months of use, they haven't loosened. I would buy them again!