Shimano BB-UN300 Vierkant Innenlager - BSA

Quality is correct, shaft bearings and seals seems to be good stuff.
But the outer ring of left bearing was not perfectly centered with the centre steel spacer on mine, so when tightening the left cup, the spacer scratched the cup and made aluminium shavings. I had to remove everything, clean and assemble again...
Plus be aware that:
- the threads of the cups are very long, you'll need probably to re-thread your frame further or file some threads on the cups;
- the shoulder on the right cup is smaller than usual: only 36 mm diameter, not compatible with all frames or chainguard brackets (Shimano BB-UN55 is Ø39-40 mm as a matter of comparison).