Boom! These 6" x 2" heavy duty reels are just what I was looking for. These are large, durable casters with a nice rubber wheel. They are mounted on a rolled steel frame that I use for towing heavy loads. The bolt pattern on my cage is 3" x 3", they work great using existing bolts from the old reels. These reels are each rated at 3600 pounds. We will see. They haven't been under a lot of pressure yet, but early prospects are encouraging. They roll smoothly and are easy to handle. Update... the rolls are holding up great. They are a definite improvement over the old bearing rollers. Reliable and smooth. Still happy.