They are all metal but not at the 350 lb level, more of a combination. The frame and mounting plates are very weak and cannot support the weight load specified in the description. The wheels have a very thin webbing that supports the outer wheel. I see these pulleys flex when loaded with 800 or 1000 pounds [which are rated at 1400 pounds]. You notice that the ad doesn't talk about heavy or light loads, just a rating that doesn't say combined or per roll. . Just keep in mind that these are light to medium weight skates.
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