A. W. Faber-Castell two-foot slide rule
A. W. Faber-Castell two-foot slide rule, with cursor graduated for power conversions.
A. W. Faber-Castell two-foot slide rule, with cursor graduated for power conversions, in box
A. W. Faber-Castell two-foot slide rule, with cursor graduated for power conversions.
Box, green, for A. W. Faber-Castell two-foot slide rule.