Seeking Guidance on Male Chastity Novella Device Sizing

I’m thinking about putting together a novella centered on male chastity. I’ve published other ebooks before, all falling into the erotic (or pornic) category, but this project will actually demand that I experience the lifestyle myself, at least to some degree, so I can better inhabit my protagonist’s perspective. This requires me to buy a device. This one seems fine for short-term wear, though I have sizing concerns. The listing says the ring diameter is 43 mm, giving a circumference of 135 mm. My own measurements (taken around the main part with a cloth tape pulled fairly tight) came in at 170 mm. Am I unusual? Is the manufacturer off? Did I measure incorrectly? Or is Chinese manufacturing generally smaller than American standards? Any advice would be appreciated.

What you're seeing appears to be the A080 or A081 model that many Chinese vendors are using. I recommend searching this group for those two terms since they've come up quite a bit. I was actually thinking about getting that specific one myself, just to give it a try.