The PowerBlock U-33 Stage I Dumbbell Set has a weight range of 3-21 lbs per hand and will replace 16 pairs of dumbbells or 352 lbs of free weights. Increments achieved with the U-33 Stage I Set are; 1, 3, 4, 5, 7, 8, 9, 11, 12, 13, 15, 16, 17, 19, 20, and 21lbs per hand. Dimensions are; 10.5"L x 5.5" H x 5.5" W. PowerBlock U-33 Stage I Set ships in 2 boxes.

The Flex Series Urethane Sets from PowerBlock are the fourth generation of PowerBlocks. The Urethane coated weight plates offer the ultimate in smooth, quiet performance in addition to Flex technology (patent pending) in both the weight plates and the selector pins making for the most durable PowerBlock ever. The steel side colored rails are powder coat painted and are on both sides of each block.