I have tried the rpm, live pro, and x fit heavy grip.. the most comfortable in hand by far were the x fit heavy grip, as they are the most non-slip. As for resistance, the most difficult ones by a huge margin are the live pro, followed by the rpm, and finally the x fit heavy grip. Keep in mind that the 280lbs live pro is more challenging than the 350lbs x fit heavy grip and doesn't have as good of a grip that slips. It is also more difficult than the 300lbs rpm that I tried. Finally, I would like to mention that I recommend them for their convenience, but I noticed something strange when I tried a friend's 250lbs x fit heavy grip, it had a larger opening and was more difficult than my own 250lbs heavy grip, so I don't know how consistent they are in the batches they produce... If you want very strong grippers, you can look at the rpm hulk 400lbs, ghp level 10 425lbs, and the captain of crush 4 (365lbs), but they are like 450+ in comparison to heavy grip.

After more than 500 repetitions, it's fine, although it makes an annoying noise and creaks quite a bit, but you can't do otherwise, since you are exercising with a metallic object. It is a very good dumbbell, I would not recommend it for small children. Overall, it's fine

I bought this one of 68 kg (150 lb) and the corresponding one of 90.7 kg (200 lb) and what I have noticed is that they have the same difficulty (I end them with the same force). It's like I bought two identical ones. While the difference of 22 kg should be significantly noticeable, since the difference between 68 kg and 40 kg (which I already had) is also noticeable. This results in me not knowing which of the two (68 or 90.7) is defective.

The product is of good quality, but the 45 kilograms I bought are not enough. For anyone who exercises, it would be better to directly get the 90 kilograms. For someone who is just starting now, the 45 kilograms will be sufficient

Nice sturdy construction! The handles don't slip - I think they're made of aluminum. Definitely worth a close-up test to find the perfect one, as there are gradations!