The powerblock u70 stage 1 adjustable dumbbells are part of the urethane series and replace 15 pairs of dumbbells or 279kg 615lbs of free weights they offer a weight range of 2 18kgs 44 397lbs per hand and are supplied as a pair in addition the set is expandable later to 27kg 595lbs per hand with the u70 stage ii add on kit and again to 32kg 705lbs per hand with the u70 stage iii add on kit