I have a near NOS naiad crown in my parts bin. It measures 6.3 x 2.9mm. Any idea what reference would be correct for this? Certainly not a speedy. TIA

 

either a speedy or Seamaster/Railmaster.
Can you measure the diameter of the stem threads?

 

looks like a SM300 crown,

dibs!

 

Looks like it’s 0.9mm. But tough to measure with my caliper.

 

0.9mm is Seamaster if I recall correctly
1.0mm Speedmaster and 1.2mm on Railmaster, I can double check my notes tonight. I think this is for 2913

 

Are the width and diameter different for speedies.? Other than stem sizes.