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The dollies arrived as a box of parts, some felt pads, and a nasty little wrench. They had to be fully assembled, down to the peel-n-stick orange felt pads. And it's a good thing the nasty little wrench was included: even with it, tightening the casters was a challenge.
The dollies worked great with the first 1250-lb cabinet I moved, by the fourth one, the casters wouldn't roll, they wouldn't swivel, and the frames were bending. These might be good up to ~1,000 pounds, but they certainly won't handle the rated 1420 lbs.