That one is just plain big! I imagine when seen in the field, there was no question about it being a good one! The tip sections are especially long so that's what separates it, IMO, from similar forms/curls that usually go 54-55". I'd guess over 55 for certain but not quite 60?? Good image to put into the gray matter memory banks for future reference. Thanks for posting.
Here's a very similar one but without the long tips. This one is 54
