I have purchased the weights in 1.25, 2.5, 5, and 10 kilograms. I have been using them for months. I have used them with dumbbells and a barbell. I mainly do exercises for legs (hip thrust, Romanian deadlift, front squat, Bulgarian split squat, and step up), but also for upper body (reverse flies and lateral raises). This review refers to all the weights.

First of all, they are not rubber, they are cement with a plastic cover. They are indeed the specified weight with very small fluctuations of 0.1 kilograms (although this could also be due to the scale). They are cheap (half the price compared to iron weights) and maybe (I emphasize maybe) with proper use, they can withstand a lot because there is no fear of rust, etc.

Now, let's move on to the negatives. Because they are made of cement, they are quite large, about 3-5 cm thick. They are not properly balanced, meaning their center of gravity is not in the center of the weight. In simpler terms, they exert torque on the barbell. To put it even more simply, they make the barbell "want" to turn towards one side. As the weight of the weights increases (and the diameter), this becomes worse. The small weights rotate but do not exert much torque, the large ones rotate so much that they move the collars of the barbell and then the weights move outward. In exercises where the weights move up and down, there is no problem (e.g. step up, deadlift, lateral raises, etc). In exercises like front squat or if someone does clean and jerk, there is a big problem. For example, when I lift the barbell with 10 kilograms and 30 kilograms on top, making the clean movement to get into the front squat position, if I do it without caution and quickly, the weights move outward by 10+ cm to the point where I put it back down. I have learned to do it relatively slowly so that this does not happen.

The conclusions are up to you depending on your use. It goes without saying that you should handle them with care. Even with 50 kilograms on a 10-kilogram barbell, which mainly rests on 2 weights of 10 kilograms, I have no problem with their durability. Perhaps they are less catastrophic if they fall (for example, iron would damage the floor tiles, while cement would damage itself). You get what you pay for, so if someone has/wants to spend more, they should go for truly rubber weights that are expensive and use an Olympic-style barbell. That's it.