Grainfather lid triclamp size

[Tombo]

Hi can someone confirm the size of the triclamp for the lid of grainfather conical fermenter please? I've read it's supposed to be 1.5" but I've measured it and the internal ID opening is 34mm and the external is 50mm so neither are 1.5", I'm probably not measuring in the right place but want to check before I go ahead and but some fittings? Thank you

 

[gyurmaember]

It's 1,5"