The Concise is the only circular slide rule in my collection (so far) with a single fixed scale and a rotating inner disk for the “slide”. The rotating wheel has C/CI/A/K scales printed on it. On the other side are a bunch of unit conversion formulas. The cursor has a compass and “Takeda” logo printed in red on the back side.
It came in a plastic case with an instruction pamphlet that had a “Key Line” logo printed in it.
Dimensions: 8 cm diameter x 0.2 cm thick.
