Hackers Help: What’s the diameter of a GRUNDTAL rod?

Hello,

I have a question about the rod-diameter of an Grundtal 47′ (120cm) rack.
I can’t find a firm answer on the Internet.
Some say 0,6″ (15mm) other 0,31″ (18mm). Do you have an answer?

~ Benjamin

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Benjamin, the one I have (a GRUNDTAL rail) measures 15mm.

~ Jules