Bowflex SelectTech seemed awesome when I first purchased it and received. It had extremely convenient dials that allowed you to select your weight without a hassle and what looked to be a pretty sweet mechanism.
The draw back? The weights lasted for a month. Even with delicate care, the dumbbells still broke on me. I have both models, the 552 and 1090 and the long-lasting quality was not there. Bowflex will give you a limited warranty for a year if you submit it during the first month. But it's limited. And they are more then willing to sell you their parts (and labour) for a marked up price.
Conclusion: They have a great design but the plastic parts will never be able to handle the everyday use of what dumbbells are intended for. If this were made of all metal parts perhaps it would of been a different story.
I wouldn't recommend anyone in buying them, no matter how gently you intend on using them. I was so disappointed in these I had to review it, which is a first.