Andy,
These are the grease seals we were talking about.
Total length - 45mm
Diam of small hole - 15mm
Height - 21mm
Diam of large semi-circle is 26mm
The thickness of the rubber in large curve is 3.5mm (ish) for most of the length, but one end is slightly thicker. Possibly a subtle design included to create better seal on the lower end. Take that, gravity!!!!
Hope this helps.