PowerBlock

I had a couple of great ordering experiences with them. During the height of the pandemic, it took a while for these to become available, but these were among the top rated adjustable dumbbells in various best-of lists, so we took the plunge and ordered two pairs.

They've been in pretty much constant use since then (September 2020)! We lift weights about four times a week and they've been easy to use and change the weight on, good for a variety of exercises, and incredibly durable. There is some difference in the form factor between these and "normal" dumbbells but with a few minor exceptions (usually involving the grips) you can do every dumbbell exercise you can think of on these.

After we received these, we realized it would help to have an easy place to put them and a place where it's accessible for adding and lowering weight, so we bought their dumbbell stands which were also effective. These arrived much quicker as we got them in 2021.

We had no issues as far as needing to contact customer service, and while there were shipping delays due to the pandemic, they were upfront about this when we initially ordered. Overall a great experience!