Buy it. Use it. Good luck on your next helmet.
The process is well thought out. You receive the wooden caliper and a link to directions on how and what to measure. Once measurements are submitted, a report is received with data on helmets vs you measurements. It took me a while to understand the data, but overall, I find this to be super valuable. Helmet fit isn’t straight forward and after you ride in it an hour or two, they usually can’t be returned. I’ve found wearing it around your house isn’t like riding in it.
I still struggle with some of the data were multiple helmet sizes are “green” or in range for me, but overall, I would recommend this tool.