Extra large Vernier calipers - photo

[bruce.desertrat]

Based on the gradations, I expect those are an educational set designed to teach you how to use them. However I do have a 24" set out in the shop that I picked up on a lark from American Science and Surplus a while back. 0.05 mm, 1/128"

Bigger than my lathe! (I've actually used them a couple of times, good for determining square-ness of box shapes (like drawers) and such...