I used these bearings to build an inexpensive railroad car from standard 1" pipe and a pan and flanged wheels that I bought off ebay. There are many different concepts of what an inch is, and 1 inch pipe doesn't go through these camps. On the other hand, the 1" wheel bore was too wide so I couldn't machine the tubes. Instead, I asked a local shop to machine the bearings. It was a bit more work than what the guy originally called, but ended up having it worked well and now all 4 bearings sit perfectly on the standard tubes.