From Wiki

Graphoplex 620

• Type: Closed Body Rietz
• Size: 11 Inches / 27 cm
• Material: Plastic
• Scales:
  • Front: B³ B² [ b² a b ] B L
  • Back: [ S ST T ]
• HvH: 1303

With inch and centimeter scales. Reverse printed with unit conversions and materials properties, in French. Unusual scale markings equate to K A [ B CI C ] D L. ST scale marked "S&T". Red paperboard box.