Dial-A-Trig

The Dial-A-Trig wheel is your guide to triangles. I don't know anything more than that about trigonometry, so you're on your own there. This wheel is 7.75 by 9 inches and someone punched it for insertion into a notebook, which means this wheel got some use. And look! When this was first printed, the patent was pending. It appears Joseph Peter Simini had to have a rubber stamp made to correct the pending part.

It looks like this is pretty easy to use. I guess.