The powerblock u90 stage 1 adjustable dumbbells offer a weight range of 2 225kg 44 496lbs per hand and are expandable to 41kg 904lbs per hand with the u90 stage ii add on kit and again to 57kg 1256lbs per hand with the u90 stage iii add on kit they replace 16 pairs of dumbbells or 374kg 8245lbs of free weights and are supplied as a pair