Circular slide rule consists of two handmade wheels, the smaller attached on top of the larger with handwritten numbers in pencil around the edges. An arrow is written in ink in the middle of the smaller wheel between handwritten lettering "O3" above and "LB-O(symbol)" below. A handwrtten note on the back reads "invented by / Charles W Bachman / circa 1953". Water stains appear on either side of note.
