I'm very happy with these wheels for three reasons: - I use these along the ocean and they do not rust - They are slightly lighter than the metal-hub wheels - They appear to be strong (my 90 lbs pressure washer has hit hard bumps with them, no problem) - They provide adequate cushioning. Not as much as air-filled tires; however, more than hard-plastic. In short, the materials are good and unless you have an extreme-duty application, these should be strong enough without the hassle of metal hubs. These include two cotter-pins and four washers designed to perfectly fit 5/8\" axels.