have work out at several gym for the past 2 year or so , these be the most versatile dumbbell I have encounter . now that I be in graduate school , I do not have as much time to drive to the gym , so I make a little home gym and add these to my collection . these weight be AMAZING . at first , I be a bit skeptical of the idea of square dumbbell , but the shape do not interfere with most exercise that you 'll be do . honestly , within 2 day , I be about to set the weight on these dumbbell within seconds . simply slide the pin in and out . I find these far more convenient than have a whole set of traditional dumbbell . I definitely recommend this product .