• Their construction is very plastic, you can see the plastic joint.
• They don't have any external layer like silicone or soft plastic, it's just a layer of plastic which is not very good because it slips...
• It's directly the cheap plastic that you can see even the sand grains it has for weight if you look at it in the sun.
• I bought 2 kg and the weights are so bulky that you would think they are at least 8 kg.
• Overall, they are good, they do their job, and they are very cheap...