Wow. These are solid, well-made skates. We overloaded a small chrome wire shelf when we needed to get all our clothes out of the closet during a renovation, and I broke one of the tiny nylon casters moving it around. I wanted something stronger for the repair and after realizing that the unit was threaded for the smaller 6mm rollers it was a bit difficult to find something solid to mount to. I wanted polyurethane wheels but settled on these as they were the largest I could find. They're a bit more expensive - note the price is for one wheel - but when I saw how durable they are it made sense. They seem indestructible and roll perfectly smoothly. And each wheel has a large, easy-to-use brake lever. The advertised load capacity of 132 pounds (per roll) is totally believable. I highly recommend these if you want a strong, smooth reel for something threaded for this size.