Also, I purchased a Gen ETB from eBay. I tried to fit it over a Gen crystal and it seems fine.
I tried to put it on a Clark’s 25-135 acrylic and I don’t think it will fit.
Do you know if that’s the wrong acrylic crystal? I think the outside diameter of the crystal is 30.5 if I’m not mistaken
Any help would be appreciated. Thank you.
One of the best posts in this thread by @1016_idiot_savant
In addition, be aware there is a difference in the date position in 4-digit dials (use Rolex Cyclop 118 #25-118, Sternkreuz XS 306.133) and 5-digit dials (use Rolex Cyclop 135 #25-135, Sternkreuz XS 307.457). Also - the 5-digit bezel fits the Cyclop 135, so make sure you pair the dial, crystal, and bezel. With this being said, everything just fits together like Lego blocks...
It would seem your gen ETB might be from a 4-digit model if it doesn't fit a Clark's 25-135.
I am not sure of the outer diameter of the Clark's crystal, but the 25-135 replacements from Otto Frei (ofrei.com) are 30.7 mm.