I also buy these for the Chalene Extreme work out which require many weight change , and they work fantastically . change the weight take some get use to , but I be get use to it and be able to make the change quickly enough to keep up with the workout video . I do a lot of research on adjustable weight , read many customer review , and visit several sport goods store to `` touch '' the adjustable weight in stock , and decide the powerblock be the way to go . I be a little hesitant as they be not returnable , and they look funny , but I be very pleased with the product . as soon as I take they out of the box , it be obvious to I that they be a quality product , and a great value in comparison to the price of all the other adjustable dumbbell set out there . I highly recommend powerblock to anyone in the market for a ajustable dumbbell weight set .