All cats should have one! This thread got me thinking of a scope I bought off ebay once. Made of brass I thought it was pretty unique and I guess someone else did too. We got in a bidding war and I spent over $70 on it. It was no sort of rifle scope at all! It had crosshairs, which close internal examination revealed to be fine human hairs that someone had glued in. It was a 8X viewing scope out of a Simplex projector! The operator in the projector room used it to get a zoom view of the screen, so he could focus on the grain of the film. Had a heck of time getting my money back, had to send it to Parsons, mentioned above, and get a letter from him verifying that it was not a riflescope. It had zero eye relief, so even a .22 would have stuck it in your eye. Now, back to Unertl. I bought an old Litschert booster to get 12X out of an early 6X Weaver. The lens in the Litschert was marked J. Unertl on the side.
"I have sworn upon the Altar of God, eternity hostility upon all forms of tyranny over the minds of man." - Thomas Jefferson