|Belt claimed to be from 16th-17th century|
Of course, my misgivings turned out to be correct. There's little evidence that medieval and Early-Modern references to the things were anything but metaphors or jokes, and the "real" ones that exist seem to date no earlier than the 18th or 19th centuries, when they were probably created as fakes to put in "medieval torture museums," or perhaps as sexual novelty items.
Here's some reading on the history of this pervasive myth.
Add this to the long list of things people "know" about the middle ages that just ain't true. As the old adage goes, a lie makes it around the world before the truth gets its boots on.