I have thought about getting these dumbbells (Pro 50) for years and finally decided to do it. I first saw them on the Fitness Blender website; Kelly and Daniel use them and have always said good things about them. I have no regrets. They were a little awkward at first, but after a few workouts with them, I got used to them fairly quickly. I love that they can rapidly switch between various weights; it helps when I am trying to keep up with my online trainer. And, they save space in my living room! I am trying to move up in the amount of weight I lift and did not want a bunch of dumbbells taking up space. 5 stars!