I have a UN55 i got in a frame 5 year ago - i think at some point its been on pretty much every bike ive built as a makeshift bb till ive found/afforded the correct one - currently sat in the Donohue but spindle is too short for record pista cranks - first time its not worked!
The un54/55 is the how all bicycle parts should be made.
You'll have bought at least two dozen bikes before it needs replacing*