I bought an old Starrett No.1025 5" Pocket Caliper this weekend (at a vintage shop) , and, wanting to know something about it, am finding values from $60 (eBay) to $300 or so. For this tiny unremarkable thing, I am wondering what I am missing. I can't imagine how it could be collectible when it has no way to determine how old it is, and why it would be desirable. Anybody have any history or info about these things?