Does anybody know? There no mention of this detail in the 1953 Ektar lens catalog on the cameraeccentric site, only that it's Series VI in front.

While I'm asking, can anyone tell me the rear cell diameter for a Supermatic-mount 127mm f/4.7 Ektar? I have a Synchro-Compur version that's 33mm and I'm curious if it's the same as its more common sibling.

Thanks!