I purchase the PowerBlock dumbbell after return the SelectTech dumbbell . the selecttech be cumbersome , the weight plate feel loose , and you have to dial two dial to select one weight . furthermore , they be over $ 100 more expensive than the PowerBlocks . on the plus side for the PowerBlocks : 1 -rrb- they take up very little space for a adjustable dumbbell 2 -rrb- they feel solid 3 -rrb- while not cheap , they be much cheaper than the SelectTech dumbbell 4 -rrb- you can do over the head tricep extension use both weight or one use the handle on the bottom 5 -rrb- select the weight be a one step process for each weight 6 -rrb- they be upgradable with a heavier handle option and a barbell option on the minus side : 1 -rrb- allign the pin to select the weight be a bit more difficult with the weight on the ground . the stand or a table top would alleviate this problem . overall , I be pleased with the PowerBlocks and definitely recommend they to anyone look for a quality , adjustable weight dumbbell .