I have been wanting these since I started adding strength training into my workout routine but I held off because heaviest I could work with was around 10lbs per hand. I am now strong enough to get good use out of these and it beats having to buy separates. Not only are these a better deal but they save space and are super convenient to quickly switch the amount of weight during a strength training superset. The base is 3lbs and you can then adjust the weight in increments: 6,9,12,15,21 up to 24lbs. The main difference between these and other adjustable dumbbells is the shape. They aren't bulky and you can hold on to them in different ways, which makes them very versatile for different exercises and even work well in place of a kettle bell. The only reason I am not giving it 5 stars is because I wish it had the side handles like the 50lbs models have.