this have to be one of the best investment I have make . I use to buy a specific weight dumbbell think that I would use it for a while before increase the weight . when I start p90x , I realize that I need multiple weight and I need to be able to change the weight fast to keep up with the video . this be where the PowerBlock weight shine . the transition between the weight be flawless -lrb- with PowerBlock Sport Tray -rrb- . I be hesitant to spend so much money on dumbbell , but I can not imagine have multiple set of weight all over my house that would probably cost much more . I have to mention that the magnet design in my opinion be superior to the Bowflex SelecTech dumbbell for a couple of reason . as mention before by other review , the SelecTech be a little on the bulky side and create awkward movement in you workout because you 'll constantly be try to avoid contact with the dumbbell . it be kind of hard to explain , but the Bowflex dumbbell extend wider with add weight . my friend have the SelectTech and he always have to wear tight clothing so the gated part of the dumbbell be not catch in he shirt . another problem be that the weight selection dial break when all my friend do be drop the dumbbell inch from the ground . I think the quality would be a little better than that . it take he forever to get a replacement . this be the main reason why I look for a alternative . I never have any such problem with my PowerBlocks and it only take I a couple of try to memorize the color\/weight indicator . the weight always seem secure and I can do multiple workout in less time with a each switch of my select weight . I recommend this product for anyone who utility multiple weight do workout -lrb- which be pretty much everyone -rrb- . you will not regret the investment .