Does anyone know the diffuser o ring size? For the one with 3 long legs.

I tried to use me caliper to get a measurement
12.0mm inner
16.0mm outer
2.5 mm thickness
Do this measurement look okay
What would be a good material to go with?

mcmaster only has 17mm outer not sure if i should take the risk aince thats 1mm wider. Unless they shrunk over the years

 

I took a chance on these and they look pretty close. Might be slightly wider but good enough. Fits in place and do squeeze in the upper intake manifold.

These are the ones i purchased. Fluorine or same as Viton