A folding "fan" scale rule: five flat steel scale blades riveted at one end into a green leather case/holder, fanning open like blades of a pocketknife. Each blade is printed in black on a light (white/silvered) ground with paired reduction scales and fine graduations; visible ratios across the blades include 1:20, 1:25, 1:30, 1:33⅓, 1:50, 1:100, 1:110, 1:115, 1:125, 1:130, 1:140, 1:150, and 1:175. The uppermost blade is marked "Faber-Castell 20-83 W.Germany." Closed, the blades nest within the green leather sheath, which has a thumb-notch and a riveted pivot at the head.