UNTESTED - stay tuned for final statement about quality etc.
UPDATE: This version fits the requirements for polished plastic. For metals it isn't that clear, so stay tuned for my test results and/or have a look at the other versions.
O-Ring Specifications (unpolished):
Inner diameter of 2.5mm
Outer diameter of 5.09mm
Thickness of min. 1.27mm
Check out all variations:
3.5cm
3mm hole 3.5cm
3.5mm hole 3.5cm
3.5mm O-Ring 3cm
3.5mm hole 3cm
2.5mm O-Ring 3cm
3.5mm O-Ring