Thanks Marcus, they are really useful to see. They look the same variants as my two, except that both mine are the same height. It looks like the optic ribbed one was made in two sizes - 11 cm and 17 cm. Interesting that the plain one on eBay is etched and mine isn't, whereas the ribbed one on eBay is not etched and mine is. I wonder why this variation in marking items? (Other than to confuse folks like me! :lol: )