High-quality impression, top functional. 5.7 cm in diameter is for my hands (XL, am 1.87 m) just right. I use the pull-ups, on the barbell and also for easy pressing in hand (my tip). Caution: With the Gripz you can overload brutally fast. Less muscles but the joints. That is why you realize that only in the next few days, this one has a long recovery periods, a month. Namely happened to me. The deduction of points there for the price. Is outrageous, but there is no alternative to my knowledge.