Antares halter sizing?

Hello! I have a very silly question. I was looking at splurging and getting my horse an Antares halter. However, I wasn’t sure how the sizing worked. The options were size 1, size 2 and size 0. And I couldn’t find a size chart / sizing guide online at all.

I have a QH that I show hunter/jumpers and all of his previous halters and his bridle are all just “horse size.” Which Antares size halter size corresponds to “horse size?”

Thank you so much!

I would think it would be the same as their bridle sizing. 1 is cob, 2 is full, 3 x-full, though I don’t see specific measurements.