PowerBlocks are the world's best dumbbells. Why? PowerBlocks are perfectly balanced. They are the heaviest, most compact and easiest to use quick change dumbbell. PowerBlock is the only dumbbell system that can expand to meet your strength needs.The PowerBlock SportBlock set adjusts from 3-24 lbs in 3 lb increments (3, 6, 9, 12, 15, 18, 21, 24 lbs) in each hand. This set has a maximum weight of 24 lbs per hand and cannot be made heavier than the 24 lb maximum weight per hand. It replaces 7 pair or 14 fixed dumbbells that would have a combined weight of 168 lbs.