This slide rule isn’t very good condition. It has been in a case. All its life slider has a crack. However, the vertical line is OK if you look inside, you can see who made it Eugene Dietztgen Co Chicago, New York DK Patent No 173660 Patent Aug 9 , 1904 there are inches marked on one side and measurements on the other side. I’m not sure what the material is made out of plus on the back there are all kinds of other types of message I tried to copy it the best I could as you know this is not a new slide rule